A. They're too strong and thus ruin the challenge of the game. B. They're too hard to catch (catch rate) and I don't really care to deal with that hassle.
Pokemon can be challenging?
Challenge Mode was decently harder if you used a full team, but not really. And HGSS is hard because of the horrible leveling curve that results in you being way underleveled for the Gyms if you don't grind. --- Official Meta Knight with his Brobat http://i.imgur.com/WvefuGH.jpg?1
I don't use them, because it's boring to OHKO everything even when your attack is resisted. It feels like I'm playing with training wheels. --- Official Zangoose of the Pokemon X board+Only member of my one-man team 3DS FC: 3609-1237-6725