Going back to pokemon, there seems to be problems no matter what rule set you choose. If you go by Smogon, then there are a lot of restrictions. If you go by choosing whatever...lol Mega Rayquaza. Not to mention evasion and one hit kill moves aren't exactly fun.
Then you have the official rules, which makes you play doubles and can actually ban pokemon for worse reasons then Smogon. I don't know if this is still true, but at one point for a while, all legendaries were banned for being legendary, which sucks because just because something is legenday doesn't make it op. *CoughRegiceRegigigasCough*
I don't know if thats still true since I heard cressilia is legal, but instead apparently all pokemon not found in the ORAS or XY are banned.
Granted, there are a lot of pokemon between ORAS and XY though.