FREE iPhone/iPad App: Super KO Boxing 2 [Mike Tyson's Punchout Clone]
I downloaded this game and have played through couple of rounds, and it has a very similar game concept to Mike Tyson's Punch Out. So far, it's pretty fun, and definitely worth a free download.
iPhone/iPod Version: http://appshopper.com/games/super-ko-boxing-2
iPad Version: http://appshopper.com/games/super...2-for-ipad