New Super Mario Bros. 2

[NICKtendo DS]

They have an arsenal of potential bosses who can be revived.
Wario, Wart, Tatanga, Birdo, Clawgrip, RPG bosses (like Goomboss)
Or finally give Waluigi a platform game debut as a boss.
It's not a bad thing that the Koopa Kids return (because they did from SMB3 to SMW), but they shouldn't be hogging the spotlight from other (potential) bosses.
Still, we have Reznor, so that's awesome.