[Question] Rom hacking question

[eishiba]

Would it be possible to make a hack where every trainer you face a screen comes up before battling. It would show you and your opponents number of Pokémon. You would be required to select the same amount of Pokémon as your opponent does. If they have one but you have 6 you can only pick one. This would make the game harder. Even more so with randomizer and nuzlocke and the level caps. If I was going to do this it would be with red blue and yellow.