I'd focus on stealthy pokemon. Ones that represent espionage, theft, assassination, underhandedness, and distraction. I haven't decided exactly which, nor which movesets, but I have a feeling either Bisharp or Weavile would be on there, a ghost or two... My favorite types are water, dark, ghost, ice, steel, and poison. Not all for their offenses, not all for their defenses, just for their roles. Maybe I wouldn't have a poison type but a couple poisoning attacks for the assassin role. My nemesis in the opposite title would be a justice-oriented leader. I've been thinking of a whole setup of a game based on these two opposites, and physical versus ethereal, where you actually start in opposite realms/on opposite sides, with a thief legendary (I had a sort of bat-fox-raccoon in mind) and mallet-hand justice legendary.
But whatever, point is, those'd be my setups. Probably would have a shedinja in there for the sake of frustrating people... and isn't there a way to steal an ally's ability? I'd have someone with that to frustrate them further with a different typing. Lol Sableye w/wonder guard. But no.
Anyway, yeah, my setup would be the Thieves Guild. Or Assassins Brotherhood. Or... some other team nickname that's more comprehensive.
"The point of war is not to die for your country. It's to make the enemy die for his."