If not, here's one I made up off the top of my head: Hypno Flower. Makes it so Mario/Luigi can hyponotize and enemy, and the player can control the enemy (to make the jump off a cliff or whatever.) Like Odd World I guess.
Mario&½. Instead of Super Mario, the powerup makes him 1½ times his size, and inbetween little and super Mario. He has to hit blocks more than once to break them. Being powered down makes him Mini Mario (with all the Mini Mario features)
Also, bring back the "little fiery Mario" bug as a legitimate powerup. (And becoming hit makes you big but vulnerable). This can also be done with other powerups as well (raccoon, ice, etc).
Let's throw in squirting Mario shall we? Instead of swimming around, sinking, and avoiding enemies in boring water levels, why can't we give Mario a form of attack that is readily accessible no matter what state he is in? I mean, no wonder so many people dislike Mario's water levels! Mario can do almost nothing underwater other than swimming most of the time.
Never drowns,but due to lack of water air(in the ground)he dies,he can throw ink anywhere,but to recharge you need to be underwater.You jump like a desperate fish on the ground,but swim perfectly in the water.
How about some power-ups based on the Mario Party 2 costumes hm?
Anchor = Pirate Mario
After grabbing the Anchor item Mario can now swing a sword to attack enemies or blocks in front of him. It also allows faster more controlled swimming in the water. It's like a combination of Raccoon Mario (without flying) and Frog Mario (without boosted jump)
Horseshoe = Cowboy Mario
Grabbing the Horseshoe will allow Mario to run extra fast and turn into a tumbleweed that rolls across the ground. The tumbleweed can roll on top of water and across spikes safely.
Spacesuit = Space Mario
A throwback to Super Mario Land 2, Mario dons a spacesuit which makes him jump higher and farther with less gravity.
Hammer = Explorer Mario
A throwback to Mario Picross, Mario wears an explorer's outfit and carries a hammer. He can attack ANY enemy in front of him, even a Thwomp. He can also destroy block that normally could only be destroyed by Bob-ombs.
Magic Wand = Magic Mario
Very rare item. After stomping a Magikoopa they may drop their wand which will bounce around. Grab it and Mario can now use the spells a Magikoopa could use. Turn enemies and blocks into coins or sometimes 1-Up Mushrooms!