We saw the new Cloud, Drill, and Rock Mario in Super Mario Galaxy 2 (Cloud Mario is currently one of my favourite Mario power-ups to have seen the light of day in a Super Mario game). I am now pondering the fact of new power-ups and have concluded with one:

Dark-Matter Mario (Dark-Matter Mushroom)- Enables Mario to use up to three dark orbs that can brainwash enemies to allow them to be used by Mario, however more major enemies cannot be brainwashed and will be paralysed for roughly 10 seconds. Mario will gain a dark-purple appearance from the Dark-Matter Mushroom and due to its origin it will mainly be found in areas submerged in darkness. 

I would like to see Mini-Mario and Giant-Mario mushrooms put into a 3D game.

Mole Mario. You can dig holes anywhere you want and not just in straight line like with the Drill.

I will judge these ideas to determine the best one.

So then he can just dig his way directly to the princess without being notice.  Nice stealth Mario.  Forget the flute in SMB3, this drill will take Mario from level 1-1 straight to the end of 8-8 or watever the last one is lol