I loved using this set I made up in 4th Gen.
Alakazam @ Twisted Spoon
Nature: Timid (+Spe, -Atk)
EV: 252 Spe, 252 Sp. Atk, 4 DEF
Info: A great interrupting lead and a check for Choice users.
Strategy: Protect on the first turn, if the move they use is a damaging move, Disable it on the second turn. If it's a non-damaging move, Encore it. Protect again after Disabling, then Encore their second move. They'll probably switch out after being Encored so you have a free turn to Psychic the oncoming Pokemon or you can blast the Pokemon with multiple Psychics should they choose to remain.
Notes: Speed is important, you must out speed the opponent in order to make this set effectve, but that's not a too much of a problem for Alakazam. It has very weak defenses, so priority moves will take it out quick. Great with entry hazards since it will force switches.
Oh one more thing, Poochyena walls this set. :|