Alakazam
(whatever ability you like, mine has inner focus but I prefer Magic Guard, and synchronize is pretty cool too)
Psychic
Calm Mind
Recover (Recover could be replaced my Miracle Eye, or Reflect, because Alakazam isn't very good at taking hits from physical attacks, making reflect pretty good as a defensive option. I've had recover save my ass a few times though, so that's your call)
(Shadow Ball is alright here, if you want to beat ghost / psychic types, and theres not too much else Alakazam can learn, so it's what I use. Unfortunately, by the time you get shadow ball theres not many ghost types or psychic types you need to beat but it is still a good move to have on Alakazam)
Reflect Might be a better option considering the double battle, because IIRC it affects both of your pokemon, you could have Alakazam set up reflect, then use calm mind and then proceed to start OHKOing everything with psychic / shadow ball.