Mario Galaxy 2 could have featured other Nintendo characters
An interesting idea was originally posed for Super Mario Galaxy 2 by Koichi Hayashida. In an interview with GameTrailers, the director revealed that his team considered including Donkey Kong or Pikmin in the Wii platformer. Ultimately, though, the idea was shot down by Shigeru Miyamoto.
"One of the early proposals that we discussed for Super Mario Galaxy 2 was the possibility of including characters from other [Nintendo] franchises," stated Hayashida. "For example, you might have Donkey Kong or Pikmin show up. We presented this to Mr. Miyamoto, but he came down pretty hard, saying that there has to be a functional reason to include characters of a certain type in a game."
The Mario Galaxy 2 director said that Miyamoto explained how the body types of characters from Pikmin weren't really suited for the Mario franchise, so it would have been difficult from a design standpoint to include enemies from the Pikmin universe in Mario Galaxy 2. This certainly makes sense, especially since the Italian plumber's enemies are usually pretty chubby so he can stomp on them with ease.
Still, even with this completely logical explanation, you can't help but wonder how Mario Galaxy 2 would have turned out if freakin' Donkey Kong popped up. After all, we thought Super Smash Bros. was a brilliant crossover series. Who's to say having a Mario/Donkey Kong crossover wouldn't be pretty damn awesome? Here's hoping we actually get to see something like this in the future, because it would definitely be one of those, "What the heck? That's so awesome!" moments.