Lee Sin. All he needs to do is get his foot on ONE of the opposing team members to totally end any opposition, add to that that you just can't lock the guy down? Yeah.
For a full team?
Lee Sin, Cho'Gath, Mordekaiser, Galio, Alistar, Morgana, Kayle, Sona, Zilean, Rammus, Amumu.
Good luck fighting that. Rammmus will be going 15.2 million miles per hour with invulnerability and CC immunity while Lee Sin/Chogath/Amumu/Alistar make sure that no one is on the ground to block his rush, and if they are, they are duct taped to the wall as well.