Pokemon Weather Mayhem ROM

Pokemon Weather Mayhem rom
When focusing on the main objectives, Pokemon Weather Mayhem is about 25 Hours in length. If you're a gamer that strives to see all aspects of the game, you are likely to spend around 40 Hours to obtain 100% completion.
 

Pokemon Weather Mayhem is a GBA ROM Hack by CannonsCreative based on Pokemon Emerald. The Hoenn Region isn't taking climate change too well. How will 16 drastic weather changes at the end of each turn impact your play? Be careful, these are stronger than Heavy Rain and Harsh Sunlight! Commissioned by TCNick3 for Twitch and Youtube.

You can download the Pokemon Weather Mayhem rom from this page and to play the game you need to download the Visualboy Advance Emulator here.

You need to download and install Visual Boy Advance and then load the rom.

For detailed instructions per device, view below.

Download the official Pokemon Weather Mayhem ROM in the (USA) version for the Game Boy Advance handheld consoles. To fully utilize a GBA ROM game, use our Cheats, Rom Hacks and GBA Roms sections. You can open the Pokemon Weather Mayhem ROM or GBA file by Installing VisualBoyAdvance on Windows, MAC, Linux, Android or IOS/iphone.

Additional Information

Pokemon Weather Mayhem is a GBA ROM Hack by CannonsCreative based on Pokemon Emerald. It was last updated on March 31, 2025.

Also, be sure to try out Pokemon Pisces.

Description

The Hoenn Region isn’t taking climate change too well. How will 16 drastic weather changes at the end of each turn impact your play? Be careful, these are stronger than Heavy Rain and Harsh Sunlight! Commissioned by TCNick3 for Twitch and Youtube.

Features

  • Modifications to all weathers to make them more “dangerous”, plus 12 new weathers.
  • All other weather mechanics set in the game already have been left unchanged (I.E. Swift Swim still works in Monsoon/Rain, Blizzard is a sure hit in Hailstorm, Sandstorm boosting special defense of rock-types, etc.)
  • A new weather is set at the beginning of a battle and at the end of each turn.
  • An expanded Hoenn Regional dex featuring Pokemon up to gen IX
  • Mechanics and features from pokeemerald-expansion, notable ones listed here
  • Updated battle mechanics to Gen IX, including ability, move, type, and stat updates.
  • Pokemon have movesets updated to the most recent game featuring them.
  • Multiple debug menus available for cheating in items, altering stats mid battle, and a battle sprite viewer for looking at the new Castform Forms.

Weather Details

  • Modifications to all weathers to make them more “dangerous”, plus 11 new weathers.
    • Harsh Sun:
      • Fire-Type move damage is boosted 2.5x
      • Water-Type and Ice-Type moves have no effect
      • Non Fire-Type Pokemon take 1/16 damage at end of turn
    • Monsoon (Rain):
      • Water-Type move damage is boosted 2.5x
      • Fire-Type moves have no effect
      • Electric-Type Pokemon speed is boosted 2x
      • Flying-Type Pokemon accuracy is boosted 2x
    • Sandstorm:
      • Non Rock-Type, Ground-Type, and Steel-Type move accuracy is cut 50%
      • Non Rock-Type, Ground-Type, and Steel-Type Pokemon take 1/16 damage at end of turn
    • Hailstorm:
      • Non Ice-Type Pokemon take 1/4 damage at end of turn
    • Lightning Storm:
      • Non Electric-Type Pokemon are Paralyzed at end of turn
    • Earthquake:
      • Non Ground-Type and Flying-Type Pokemon take 1/8 damage at end of turn
    • Ether Storm:
      • Psychic-Type move damage is boosted 2.5x
      • Fighting-Type and Poison-Type moves have no effect
      • Normal-Type move damage is cut 50%
    • Pollen Storm:
      • Grass-Type move damage is boosted 2.5x
      • Bug-Type Pokemon speed is cut 50%
      • Non Grass-Type Pokemon take 1/16 damage at end of turn
    • Tornado:
      • Flying-Type moves have double accuracy
      • Non Flying-Type Pokemon accuracy is cut 50%
    • Regular Day
      • Normal-Type moves damage is boosted 10x
    • Humid:
      • Bug-Type move damage is boosted 2.5x
      • Non Bug-Type Pokemon take 1/16 damage at end of turn
    • Fog:
      • Psychic-Type move damage is cut 50%
      • Ghost-Type Pokemon speed is boosted 2x
      • Non Ghost-Type Pokemon accuracy is cut 50%
    • Lunar Eclipse:
      • Dark-Type move damage is boosted 2.5x
    • Acid Rain:
      • Grass-Type and Steel-Type Pokemon take 2x more damage
      • Non Poison-Type Pokemon are Poisoned at end of turn
    • Rainbow:
      • Fairy-Type move damage is boosted 2.5x
      • Dark-Type and Dragon-Type moves have no effect
    • Solar Flare:
      • Dragon-Type move damage is boosted 2.5x
      • Normal-Type move damage is cut 50%
  • All other weather mechanics set in the game already have been left unchanged (I.E. Swift Swim still works in Monsoon/Rain, Blizzard is a sure hit in Hailstorm, Sandstorm boosting special defense of rock-types, etc

Known Bugs

  • Castform Specific
    • Castform changes to the next weather form before the weather states to be changing. (Has no mechanical implication)
    • Castform does not change to new form on switch-in if it’s a new weather added
    • New Castform forms all use the normal castform as Box/Party sprite
    • New Castform form shinies are not properly implemented
  • Weather Ball in new weathers do not have a graphical difference. They call the corresponding type for the weather, so it mechanically works as intended
  • Enemy AI does not take new weather effects into action selection calculations. (This will probably stay unchanged because it’s really funny)

Useful Links

Discord

Documentation

Github

File Name

Pokemon Weather Mayhem

File Size

15.6MB

Version

1.0

Release Date

World: March 31, 2025

Genre

RPG

Developer

Platform

Game Boy Advance

Region

USA

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