Pokemon Jupiter is a ROM hack of Ruby.
The character you play is as Ivan from the Golden Sun games. There are elements from those games incorporated in Jupiter but it is still a Pokemon game never the less.
Speaking of the Pokemon, the game has a mixture of random Pokemon from different Generations and a plethora of Fakemons that you can catch, train, evolve, and use in battle.
Story
Despite elements of Pokemon Jupiter being based on the Golden Sun games, the story is a bit unique. Your character Ivan and Charon reside in the Mynoan Civilization.
A great calamity is headed to the Mynoan Civilization and Ivan along with Charon escapes to the Pokemon World. They are separated and Ivan meets up with a young trainer named Rachel.
After saving her, he receives his own Pokemon and must traverse through the Pokemon World to find Charon and fight some Gym Leaders along the way.
Features
The Pokemon roster is made up of those from Generation I as well as randomly picked ones from other Gens. A lot of the Pokemon that make up the roster are Fakemons with very interesting designs.
The game also has unique musical tracks and altered sprites for some of the characters and Pokemon. The gameplay is the same and it has a lot of influences from the Golden Sun games.
Feature List
Elements from the Golden Sun games are present
A mixture of miscellaneous Pokemon different Gens and Fakemons
An array of unique musical tracks and weird sound effects
There is a Telepathy feature that allows you to converse with some Pokemon in the field
I have a lot of games listed for sale. If you were interested in more than 1, I have large group listings that show all of my games. I have one for the GBA, GBA Custom Pokemon ROM Hacks, and NIntendo DS Games.
GBA Pokemon ROM Hacks - https://www.bonanza.com/listings/Pokemon-Custom-ROM-Hacks-GBA-Game-Cartridge-Lot-Variery-Rare-Nintendo-Game-Boy/1612209981
Nintendo DS Games - https://www.bonanza.com/listings/Nintendo-DS-Video-Game-Cartridge-Huge-Collection-Pokemon/1626170709
Gameboy and Gameboy Color Games - https://www.bonanza.com/listings/GBC-Pokemon-WarioLand-Legend-of-Zelda-Video-Game-Cartridges-Bundle-Lot-Deal/1640420407