Welcome to PokéCommunity! Register now and join one of the best fan communities on the 'net to talk Pokémon and more! We are not affiliated with The Pokémon Company or Nintendo.
I have a similar problem, but I didnt add any pokemon to the ROM only changed some colors of some pokemon.
I am using Nameless Sprite Editor and it opens up and everything works until I try to open the sprite of one of those pokemon. The others dont seem to have such a problem. If I am ingame...