man 1: stealth
man 2-5: anything
The Idea behind this tactic is surprise. It is not an ideal tactic to go into a game and plan on using, however if your team is pinned down then you can use this tactic effectively in order to get win.
man 2-5:
man 2-5 can have any class, any weapon. Whatever they're using at the time is fine. their only job is to keep the enemy busy. Basically engaging in a firefight with the enemy.
Stealth:
The ideal stealth class would be
UMP45 silenced
any silenced shotgun
semtex/frag/tac insert
stun/flash
Perks
Marathon
Cold blodded
Ninja
The job of the person being stealth is to sneak up behind the enemy and get away from their own team. In order to do this they have marathon to move fast, cold blodded so that they can't be detected by killstreaks, and ninja to be silent. the whole job of stealth is to be unseen and unheard. Once they get behind the enemy they should take out the one closest to them, then the next. knifing if they can.