All 898 shapes and variants are coded in game so you can get them with the random number generator.
Also try Pokemon FireRed and LeafGreen Plus. You can basically meet and catch all 898 Pokemon if it’s randomized since the spawns are normal if you play the game regularly. This hack has more features like the Dynamax feature if you activate it at the beginning of the game. You can choose one of these things or all of them at random. Even before you leave your room, you must randomize the Pokemon that spawn (including starters), the skills that Pokemon can learn, and the moves that they learn as they level up. While you can play this ROM hack normally, the question is, why would you? The best feature of this game is the ability to randomize some things. Just be aware that the Pokemon that spawn in the various locations will differ from those in FireRed, and some will be the same.
If you’ve already played the game, then you know what to do, where to go, and what to expect. The story is the same as in Pokemon FireRed. Pokemon FireRed 898 random number generator details and more Story