Personally I think the problem is XP system that force pokemons not to evolve until max level. While evolutions is one of the most interesting feature in pokemon games as the awesome feeling seeing your baby pokemon grow stronger and stronger through many forms. It is boring if you spend almost all your adventure with a basic pokemon until it is level 100, until your pokemon become more awesome than ever and then you realize that most of things to use that power on have gone. So I think it is better not make the XP required to levelling so much more after evolutions, even if it does please make it a little so trainer have more choice that keep basic form for a bit faster leveling or enjoy stronger forms. Hope this helpful and ... love this game :)
