Metagross is more of a physical sweeper, though... most psychic types are used for special sweeping. Although, 'Gross could make a special sweeper (Modest nature, 252 EVs in SpAtk). However, it almost ruins the point of 'Gross, so I don't suggest it.
Gardevoir is a popular psychic type, and Mr. Mime is occasionally used, but Alakazam is still the best, even with his now semi-limited movepool.
Also, Hidden Power is mostly used for Net Battles, unless you get lucky in your game. If I had to choose a special sweeping moveset for 'Zam, this would be it:
Calm Mind
Psychic
Shadow Ball/Focus Blast
Focus Blast/Energy Ball/Recover
Recover isn't the best, it's more of a novelty, since 'Zam's defenses are too bad to give it decent recovery time. Energy Ball is grass, but can take down ground and water (replacing Thunder Punch in the case of waters), although grass isn't the best attacking move, and Focus Blast is Fighting (which makes him capable of taking down one of his worst weaknesses: Dark types), if it hits, of course. Guard Swap (an Egg Move) could also come in handy, if up against a big beefy Pokemon that has high defenses (Guard Swap switches both defenses with the foe). However, he can learn no decent Fire type attack, so now Metagross will easily take him down. Shock Wave or Charge Beam is also an option, but doesn't pack enough of a punch to be considered by me.