Do you have both the .pac files and the .pcs files? For characters that transform, you need both.
That wouldn't stop the texture from loading though, it would revert them back to normal after transforming. The problem might be that you've named the folders and the files for the pokemon incorrectly. Check that they are called:
Charizard - PokeLizardon
Ivysaur - PokeFushigisou
Squirtle - PokeZenigame
Oops. My bad. Yeah, listen to AdfroMan, he just might be on to something. Thanks to the files using the Japanese names, it can be pretty easy to get either the names of the folders wrong or the names of the files wrong.