Who do you think will be the bosses of the story mode?

[Jimmy T.]

Yes, indeed the 12 bosses work for Bowser. DK and Diddy Kong have no affiliations with Bowser at all.

They don't even work for him at all!!

Remember the last time that they rescued Mario and friends when they were tiny back in Mario Party DS?

Well, they didn't technically do so, they came for the food. They bumped into Bowser on purpose and smashed the Minimizer Rod, therefore returning Mario and his friends to normal size. Otherwise, they would probably still be small in Mario Party 9.

Even with Mario Kart Wii and with further games in 2008 to present. I know they didn't technically rescued them. But, just saying.