Pokemon Heliodor ROM

Pokemon Heliodor is a GBA ROM Hack by Citrus Bolt based on Pokemon Emerald in English. It was last updated on February 05, 2026.

Description

This is a modification of Pokémon Emerald intended to be an interpretation of the “definitive” Generation 3 Hoenn concept while still fitting firmly within the official game ecology.

The highest design priorities are 100% compatibility in terms of:

• Multiplayer
  • No changes made should interfere with any link capability with Pokémon Ruby, Pokémon Sapphire, Pokémon FireRed, Pokémon LeafGreen, Pokémon Emerald, Pokémon Box Ruby & Sapphire, Pokémon Colosseum, or Pokémon XD: Gale of Darkness.
• Inter-generational Transfer
  • Every Pokémon obtained should completely be legal (indistinguishable from a Pokémon obtained in an official game, using PKHeX‘s legality checker as the reference as opposed to Game Freak’s) once transferred to a Generation 4 game, with one outlier.
  • The exception to this will technically be illegal until it enters a Generation 7 game, but there should be no issues transferring it through Poké Transporter to Pokémon Bank.
• Save Files
  • There should be no (significant) issues importing your save file from Pokémon Emerald to Pokémon Heliodor and vice versa.
  • This allows Pokémon Heliodor to, in effect, be treated similar to an expansion pack in which if a player has already completed Pokémon Emerald, this can be used to “unlock” extra content/features for that playthrough.

Features

• All 386 Pokémon available within Generation 3 are obtainable.
  • Pokémon not normally found in Pokémon Emerald are generated with different game IDs, languages, and pseudo-random number generation methods to replicate the encounters in which they can normally be found in other games.
  • This includes new wild encounter tables post-National Dex acquisition, additional gifts, in-game trades, and an extended roamer quest.
    • If importing a save file from Pokémon Emerald after capturing/defeating the roaming Latias/Latios, speak to the new NPC at the Weather Institute to force the next roamer to initialize.
• An egg incubator is available for use that relies upon the real-time clock instead of the step counter.
• All tutor moves found in Generation 3 games are available for purchase at the Battle Frontier.
• Moves learned by level-up exclusively in Pokémon FireRed and Pokémon LeafGreen are added to the learnsets.
• Evolution items and Kanto-exclusive held items are available for purchase at the Battle Frontier.
• The remainder of the Kanto-exclusive items are available at the Lilycove Department Store.
• For Pokémon Colosseum and Pokémon XD: Gale of Darkness players, Poké Coupons that have been transferred to the cartridge can be used to purchase rare items.
  • Poké Coupons can also be obtained by trading in Battle Points at the Battle Frontier.
• e-Reader functionality has been restored with version and language restrictions removed.
  • The Legendary Titan dolls can be obtained without issue.
  • e-Card berries can be obtained, although Japanese berries will (obviously) have text errors.
    • The Game Boy Kid in the Cove Lily Motel has an e-Card to scan, allowing an e-Card berry to be obtained without having access to an e-Reader.
  • The Eon Ticket can be obtained, but the event text is slightly garbled.
    • The Eon Ticket can also be obtained during normal gameplay after defeating the Elite Four for the first time.
  • e-Card trainers will be saved, but can not actually be found to battle.
• Altering Cave’s wild encounters cycle through the unreleased Mystery Gift tables every day.
• The Pokémon summary screen now shows correct information for all locations in Pokémon Ruby, Pokémon Sapphire, Pokémon Colosseum, Pokémon XD: Gale of Darkness, as well as Pokémon CrystalDust.
• Breeding mechanics have been changed.
  • Both parents can now pass down Nature and moves.
  • The “Masuda Method” is implemented.
  • A bug affecting IV inheritance has been fixed.
• If the first member of the party is holding a Scope Lens, only Pokémon of that species will be found in the wild as long as that species is available at that location.
• Methods to aid in obtaining Shiny Pokémon have been added.
  • As mentioned above, the Masuda Method is implemented.
  • Once the National Dex has been completed, Shiny Charm functionality is activated. (no item needs to be obtained for any of the Charm effects)
  • Successively encountering the same species of Pokémon will increase the odds of encountering a Shiny Pokémon.
• Once the Hoenn Dex has been completed, Oval Charm functionality is activated.
• Once the Elite Four has been defeated, Exp. Charm functionality is activated.
  • Catch rates are also boosted by 50% at this point.
• Net Ball, Dive Ball, and Repeat Ball mechanics have been updated to match the changes made in Generation 7.
• If any member of the party holds an Exp. Share, the whole party receives experience points from battle.
• Legendary Pokémon (and Sudowoodo) that have been defeated without being caught will respawn when the Elite Four is defeated.
  • The respawn will only trigger if the Pokémon is not registered as “caught” in the Pokédex, so trading over a legendary Pokémon will interfere with this.
  • Roaming Pokémon will respawn instantly somewhere in the region when knocked out.
  • After every 10 Elite Four victories, all Legendary and Mythical Pokémon (and Sudowoodo) will respawn whether they’ve been captured or not.
• The clock offset can be changed by pressing ‘B’, ‘Left’, and ‘Select’ on the title screen.
• Secret Power, Cut, Surf, Strength, Rock Smash, Waterfall, and Dive can be used as long as one of the party members is capable of learning the move.
  • The respective badge is still required.
• EVs are capped at 252 per stat instead of 255.
  • The cap on EVs able to be earned through vitamins has been removed as well.
• The battle and summary screens report the correct type and base power for Hidden Power.
• Synchronize’s field effect is 100% effective.
• If the first member of the party has Lightningrod or Flash Fire as its ability, there is a 50% chance of finding a Electric or Fire-type Pokémon respectively in a wild encounter if an applicable encounter is possible in that area.
• Catching a Pokémon yields experience points.
• All TMs are purchasable.
• HM moves can be forgotten without the use of the Move Deleter.
• Trade evolutions can be triggered be leveling up in the Union Room.
  • The Union Room can be entered without the Wireless Adapter connected.
• Level-up evolutions can be triggered at level 100 by using a Rare Candy.
• The IV Judge at the Battle Frontier gives specific numbers for all stats.
  • Next door, there is an EV Judge as well as an EV Reseter.
  • An IV Judge is also at the Day Care on Route 117.
• A clock has been added to the start menu.
• Pokémon have slight differences in coloration that varies with the individual.
• Eggs are colored based on the Type(s) of the Pokémon inside.
• A system similar to Pass/O/Rotom Power has been added and can be accessed through the Power Pad, a Key Item found in the Bag by default.
• The real-time clock effects the world visually.
• Trading restrictions with all Generation 3 games besides Pokémon XD: Gale of Darkness have been removed.
• A Premier Ball can be obtained as a gift for every 10 Poké Balls (of any kind) purchased at the Poké Mart.
• After a Repel’s effect wears off, and if the player has more Repels in their Bag, they will be asked if they would like to use another immediately without having to go into the menu.
• Holding ‘B’ while surfing will cause a movement speed increase.
• The Bag inventory can be sorted.
• Two more Key Items can be registered to ‘L’ and ‘R’ to be used in the field.
• Numerous small features and graphics have been changed/added and bugs have been fixed.

Known Issues

• If the game is saved on a map that has contains a new NPC and transferred to Pokémon Emerald, the game will freeze if the now-invisible NPC is spoken to.
  • This should not be a big deal, since leaving the map removes the issue, so it seems unlikely major progress can be lost this way.
• If an e-Card berry is obtained, the description text will be offset by a variable amount when viewed in Pokémon Emerald. The berry’s actual functionality should be unaffected, however.
• If one of the new roaming Pokémon is caught in Pokémon Emerald, it will not have the correct origin game ID.
  • If you are swapping your save file between versions, only capture roaming Pokémon while playing Pokémon Heliodor.

Changelog

05-02-26

• Save data has been restructured to support new features and items.
  • Because of this, save data can no longer be used in Pokémon Emerald.
  • Save data from Pokémon Emerald can still be used in Pokémon Heliodor, however, through the use of the built-in save converter that will run automatically.
  • It is highly recommended to create a backup of your save data before launching this release as the converter has not been as comprehensively tested as I would like yet. Please let me know if any issues arise.
  • Certain functions in PKHeX will now corrupt save data due to the new structure such as Bag or Pokédex editing.
• Rumble functionality has been added.
  • This works both with cartridges containing a rumble motor and with GameCube Controllers when playing on a Game Boy Player.
• Wild Pokémon generation code has been completely overhauled to better emulate official generation math.
  • Headbutt as a Field Move to encounter wild Pokémon is not currently usable.
• Wild encounter tables have been restricted to better fit Pokémon canonically found in the Hoenn region.
  • It will not be possible to catch all 386 species until Kanto and the Sevii Islands are fully accessible.
• The Hoenn Pokédex has been expanded.
• More design changes have been added to the Trainer Card.
• Additional game options have been added.
  • The color of the message box can be changed.
  • The text font can be changed.
  • Measurements can be displayed in the metric system.
  • The option to give a Pokémon a nickname when it is caught can be disabled.
• The PC in Secret Bases can now be upgraded to access the Pokémon Storage System.
• A new animation will play when a wild Pokémon appears that has two or more IVs equal to 31.
• Specific e-Cards will cause special Pokémon Trainers to appear in the Battle Tower.
• Pokémon over level 50 can be entered into Battle Tower Level 50 Mode.
  • Pokémon that were met at a level over 50 are not eligible for this due to legality constraints for the Winning Ribbon.
  • Pokemon that are under level 50 will have their level temporarily increased to level 50 in this mode.
• Pokémon move learnsets have been expanded to include moves learnable by their pre-evolutions and moves learnable in Pokémon Diamond, Pokémon Pearl, Pokémon Platinum, Pokémon HeartGold, Pokémon SoulSilver, Pokémon Black, Pokémon White, Pokémon Black 2, and Pokémon White 2.
• Like in Pokémon Ruby and Pokémon Sapphire, Sketch can be used to learn Metronome, Mimic, and Transform in certain situations.
• Traded Pokémon can be given a new nickname.
• More details are displayed in the Pokémon Summary Screen and battle move selection screen including move type/category and Pokémon origin information.
• Pressing ‘B’ on the main battle menu will move the cursor to “Run”.
  • When attempting to run from a Shiny Pokémon, a confirmation prompt will appear.
• When releasing a Pokémon, if it is holding an item, it will automatically be moved to the Bag.
• Poké Mart inventories have been updated.
  • Some Poké Marts sell new varieties of Poké Balls, but they are currently unusable.
• Lottery Corner and Pickup rewards have been updated.
• A prompt will now appear to place items obtained through the use of Pickup directly into the Bag.
• Steven has his Champion title.
• The low health sound effect stops playing after some time.
• HP bar updates are slightly faster.
• Save location now displays as more specific for certain maps.
• A Game Freak logo has been re-added to the intro sequence.
• Using Flash will light up the entire screen.
• More custom overworld sprites have been added.
• Sprites have been added for Japan-exclusive e-Card Berries.
• After healing at a Pokémon Center, the player character will automatically turn around.
• Using the Trading Board in the Union Room will no longer crash the link connection.
• Some time-related issues regarding H-Powers have been fixed.
• Numerous graphical errors have been fixed.
• So much under-the-hood work that will most likely not be apparent from the player’s perspective.

V007

• The Trainer Card can now be customized at a terminal in Pokémon Centers.
  • When linking with Pokémon Ruby, Sapphire, FireRed, and LeafGreen other player’s Trainer Cards are now displayed as they are in the player’s game.
• Numerous graphical changes have been made.
  • Tiles and overworld sprites have been modified to fit the style of Pokémon FireRed and LeafGreen.
  • The Summary Screen has been reworked and now resembles the Summary Screen in Pokémon Diamond, Pearl, and Platinum.
  • The Bag has been reskinned.
• Text has been decapitalized to match the style of Generation 4.
  • A few text issues have also been fixed.
• Event tickets can now be shared with other players via Mystery Gift and Record Mixing.
• Pokémon can now be found in puddles and in trees through the use of Headbutt.
• Standard encounters in grass now have a 10% chance of being a Double Battle.
• Mass Outbreaks have been redesigned to be more common and more diverse.
  • Swarming Pokémon are also now more likely to be Shiny.
• Two new Powers have been added.
  • Prize Power now affects money earned from Pay Day.
  • An active Power can now be cancelled to start a different one
  • Power Points now get wiped when starting a new game.
• A prompt will now appear to place a newly caught Pokémon’s held item into the Bag when sending the Pokémon to PC storage.
• “B” is now accepted as valid input when sending a newly caught Pokémon to PC storage after nicknaming it.
• The nurse at the Pokémon Center now has different greetings depending on time of day.
• Encounter mechanics have been altered.
• A bug has been fixed that stopped wild Pokémon from being found under breakable rocks.
• Fly can now be used without actually learning the move.
  • The check for Surf has been fixed.
• Mewtwo no longer respawns early.
• Roamer quest respawn mechanics have been altered.
• The main menu items have been changed.
• The Battle Frontier in-game trade has been fixed.
• The Unown event is now triggered correctly.
  • The encounter rate during the event has been lowered.
• Certain cases of illegal PID and TID generation have been corrected.
• Pokémon can now gain EVs through battle after they reach level 100.
• Experience point mechanics have been slightly tweaked.
• Catch rate mechanics have been tweaked slightly.
• Pokémon with high friendship levels now gain various bonuses in battle.
• e-Reader Trainers now correctly represent the Class printed on the card.
• Move targets now persist between turns in double battles.

V006

• A system similar to Pass/O/Rotom Power has been added and can be accessed through the Power Pad, a Key Item found in the Bag by default.
• 38 gift Pokémon Eggs have been added including Starter Pokémon and Pokémon knowing moves they are otherwise unable to learn.
• A new unique color variation specification has been implemented.
• Pressing “SELECT” on a ribbon will “equip” it to a Pokémon to give it an epithet when it enters battle,
  • This will be a “secret” feature until I get the UI figured out at some point.
• A new event involving the Unown has been added.
• All legendary and mythical (and Sudowoodo) encounters now reset every 10 Hall of Fame entries.
  • The roaming quest and Southern Island encounters are interlinked so that they will only respawn if all roamers and the Latias/Latios on Southern Island are captured.
  • Every respawn will also cause Latias and Latios to swap roles/locations.
• The day/night cycle now functions on Birth Island, Navel Rock, and Faraway Island.
• When linking with Pokémon Emerald, the other player will now appear in their green outfit.
  • Gold/Kris sprites will also be displayed when linking with the fork of Pokémon CrystalDust found on this account.
• Master Balls are now obtainable from the Coupon Exchange.
  • The Poké Coupon/Battle Point conversion has been tweaked to eliminate a loophole that allowed the player to pull a profit by trading back and forth.
• Movement speed while underwater has been increased.
• The Acro and Mach Bikes can now swapped via the Bag.
• Oval, Shiny, Catching, and Exp. Charms will now appears in the Bag once unlocked.
• Pressing “R” on the start menu is now a shortcut to save the game.
• Pressing “R” in a battle with a wild Pokémon is now a shortcut to use the last used Poké Ball.
• Soothe Bell’s effect now matches its behavior in games released after Pokémon Emerald.
• A random hidden item will now respawn every day.
• Miscellaneous text strings have been changed.
• The issue similar to the Berry Glitch that occurs after replacing the RTC battery should no longer occur.
• A bug introduced in v005 that caused a particular event Pokémon to be corrupted has been fixed.
  • If this happened to affect you, please reach out and I will fix your save file.
  • This Pokémon is also now blocked from learning 3 moves that it can not legally learn.
• A couple visual bugs have been fixed that occurred when Pokémon level up.
• A bug has been fixed that caused the Battle Point balance window to remain on-screen longer than it should.
• The Poké Coupon balance window now disappears more cleanly.

Useful Links

Pokecommunity

Reddit

Github

Discord