Uh.. no. You should find a rulebook and read it. It'll probably answer everything else that you're probably going to ask if you started with this question...
Lv. X's has a maxiumm of 4, though without the Pokémon it levels up from, it's useless, thus limiting it to 2. They share the same name, thus only 4 copies are allowed.
EX's can be 4. No, they aren't the same name as the one without the EX in it.