Terran vs terran: wraiths and/or dropps. Only metal units. In late game, BCs + tanks.
Terran vs protoss: Tank pushes with tanks + vultures. In mid game, add golls in the push and do cliff dropps if possible.
Protoss vs terran: Fast goon with range, then start pumping goons, lots, DTs and some HTs with storm for backup. In lategame use carriers + zealots to kill the enemy's bases and to hold back tank pushes.
Protoss vs protoss: Dual gate zealots or fast goon, then reavers + dragoons. Keep making reavers and dragoons. Then some more reavers and dragoons... thats basically all u do in this MU. Get some HTs in late game for support. Sometimes u should get carriers too, depends on the situation.