Alakazam- [spd or sp.att + / atk - ] @ lum berry/petaya berry/salac berry
EV: SpAtt and Spd
-Psychic
-Calm Mind
-Recover/more elemental punchs/sub
-ice punch/fire punch/thunder punch
theif doesn't work when you have an item, plus you won't survive the turn after you theif. if you're buffing up, then perhaps get recover along the way. If you're not going to use recover, then take even more elemental punchs to get more variety and be ready to sweep with petaya or salac berry. You... may even want to try subbing Alakazam to make life easier activitating berries to sweep.
Machamp- [atk + / spd or sp.att - ] @ leftovers/chesto berry
EV: Attack and HP
-rock slide
-revenge/focus punch/brick break/cross chop
-light screen/sub/rest
-earthquake
Since you have revenge there already, I just tried to work around that with part of the moveset. Lower your speed so revenge has even better chance of working. Rock slide against flyers, with earthquake just for sweeping purposes. Light screen is to help the whole team against sp.att and to make machamp possibly stand up to one sp.att. Sub/Focus Punch combo works very well too as Machamp isn't bad in physical def. It's worth considering about. You can also try rest for durability with chesto berry. Brick break or cross chop can be used for simplicity's sake if fpunch/sub is too risky to you.
Golem- [atk + / sp.att -] @ quick claw
EV: Atk and Def
-rock slide
-earthquake
-return/brick break/double edge/counter
-explosion
Very simple... attack until you're too weak then take the opponent down with you. Double edge can be used instead for more power (who cares about recoil when you blow up?). Counter can be used for HP-Grass luring (give thanks to Kairi for this idea)
Kingdra [sp.att + / atk - ] @ leftovers
EV: Sp.att and Spd
-rain dance
-hydro pump
-ice beam
-rest
Yes hydro pump, not surf. The difference between hydro and surf is a dead metagross and you half dead, or the other way around. Rain dance helps Gorebyss's swift swim too. Both of them having swift swim results in a very scary team of fast special sweeper.
Gorebyss [sp.att + / att - ] @ leftovers
EV: Def and Sp.Att
-amnesia
-surf
-psychic/HP special
-rest
Gorebyss can be highly endurable after using amnesia. Surf for STAB damage, and another special attack that you need. Use HP to get it.
Gengar 1 [spd + / atk - ] @ lum berry
EV: Spd and Hp
-will o wisp
-sub/perish song
-seismic toss
-confuse ray
i guess I'll make it annoyer so there won't be an overwhelming amount of special attackers... should be quite easy to see the plan. However i've never used gengar on 2vs2... o.o;