I have a few suggestions for the game but one in particular stood out from all of the others mainly because it's uncommon and/or never been spoken of. My suggestion is to add a pokemon that has only been played in one episode out of the entire pokemon series to be in the game. Just like how there's a Red Gyarados, I believe there should be a Crystal Onix.
Crystal Onix is an extremely rare Onix with crystal like features and because it's made entirely up of crystals it should be a rock and ice type. In the anime it also showed that it was weak against fire but immune to water. Overall, I suggest Crystal Onix to be implemented in the game but because of it's exclusive rare appearance in the anime, I also suggest for it to be an event or quest but players may only encounter it once. Tell me what you think.