Hey, pntzoee, I'd like to say two things. First, you CAN play with the controler in slot 2. Heck, I've done it in slot 4! Second, did you know that you can play as Peach? Here's how:
Gain all 120 stars, go get the 100 lives from Yoshi, and beat Bowser in the Sky (personally I think the first Bowser battle should be in the Sky and the third in the Dark World). You must repeat this 100 times, without dying once, and getting the 100 lives from Yoshi every time. Peach has all of Mario's moves and says "yah!" all the time. There are many more cheats in SM64, plus the fact that if you can play as Peach you can probably play as Luigi.
Mario, Mario, Mario! What happened to Mr. Andretti?