Aside from the multiplayer mode, there is an arcade mode, a survival mode, and a long list of challenges and well-conceived mini-games that really round off the title nicely. And since no respectable fighter can be without unlockables, everything from bonus characters to 25th Anniversary artwork is available to be won.
In the end, though this may be a game that will lie in the shadow of its grander predecessor, Teenage Mutant Ninja Turtles Smash-Up does indeed bring something to the table that even the dedicated Smash Bros warrior shouldn't mind trying. And indeed, many of us have a special, kitchy place in our special, kitchy hearts for the franchise that could very well serve to bridge the gap. So if you're a fan of Master Splinter's band of heros in a half shell, then by all means, buy, enjoy, and keep those nunchaku spinning.