Petey Pirahna hits a 300 yard STRAIGHT HIGH drive in Toadstool Tour. Do you need ANY other reason for him to rock?
Anyways, as idiotic goes, I think Koopa the Quick from SM64 fits the category pretty good. He thinks that the best way to beat Mario is not by PRACTICING, but new new shoes! How (shal)low can you get?
Another idiot is Smithy from SMRPG. You might be wondering why, but think about it. How long would the game take you if Smithy had sent Yaridovich or the Axem Rangers or even Bowyer to the Mushroom Kingdom? No, EVERY RPG villian makes the same idiot mistake and sends his/her weakest minions to the eariest areas so that the hero is ready for the tougher ones later in the game. Why not just send Yarid out there first and clobber EVERYTHING?
Those are two examples. I know there is more. I mean, Bowser in Paper Mario losing after being able to grant any wish he wants is pretty much grasping defeat from the clutches of certain victory. Ah well.
CONCLUSION: If I were a Mario villian, my game would take way too long to beat.
~I.S.~