A question about the Super Guide feature in Mario and Donkey Kong: what's the catch of using it? Does it change the ending? Do you miss out on something when having used it?

You don't get the shiny stars for beating the game (NSMBWii). Also, the super guides don't grab the special tokens so it won't unlock any extras for you.

Thanks. But when having used the Super Guide only 1 time in DKCR, does that mean I missed something on my save file when finished the game?

No, nothing like not getting a star in your save file happnes in DK. As already said, you only won't keep any of the itens got by Super Kong on the stage.

I did not know this

The other difference not yet mentioned in this thread is that when Super Guide clears a stage, it does not put the proper cleared color on the map for the stage. (IIRC, NSMBWii went to green, and DKC:R doesn't change the color at all.)

What games have had the Super Guide so far?  Just NSMBWii, Galaxy 2 and DKCR?  Didn't a DS game use it too recently (Mario Vs. DK 3)?