I don't believe that there is a way to just modify the existing system for this. What you would have to do is put a branch in the level-up code, check for an evolution ( by branching, again, to the evolution area -- see Jambo51's threads/posts for this. ) and then return. I believe that's it, but it might be a bit more complicated than that. I'm sure that there's lots of checks and balances, and such. But you would also have to re-copy the sprite info, unless you intend to show the evolution animation.