There's been many a thread on this. Think about it: a pokemon uses a Water/Grass type attack on Golem. This pokemon happens to be Ludicolo. A bit too overpowered, no?
yeah.. plus all the types would be too confusing, especially for a game aimed at children (even though a lot of us older people like it too)
I kinda liked the first part though, say a move with like 160 power (kinda ridiculous, but play along) but you have to find like 4 different pieces of it and say the pieces are well hidden, I don't know, I like it