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it is among experienced players. gligar has a nice base defense which can let him get a sub on something like pinsir or hitmonlee, and their rock slides have a good chance of not breaking the sub. rock slide on gligar is really only for fearow and stuff.
dunsparce isnt supposed to be strong, hes supposed to use his abilty for 60% headbutt flinch and 30% full para. you dont have to have a strong move to do a lot of damage as long as they cant hit you, like wrap/fire spin in rby.
in uu, scyther is the primary flailer, usually @liechi and [hp bug/hp flying]/rev/sub/sd. i like bug so it can kill hypno/pig with the help of swarm. i run qa over sd just in case, and sd doesnt help all that much.