We last saw Bowser Jr. as the most recent antagonist in a Super Mario Game, this was in Super Mario Sunshine. A new antagonist that would make regular appearances in Super Mario games would be an intriguing idea from Nintendo. Though would he/she be a Koopa, Goomba, Cheep-Cheep etc. or a new species of animal. I have a suitable idea which I will now show: A Kumarian (Bear like creature) known as King Vires manages to become as Bowser's main assistant. He left his kingdom for unknown reasons and discovered the Mushroom Kingdom. He now tries to destroy Mario as opposed to Bowser capturing Princess Peach. His main attribute is his ability to wield various rocks and throw them at his opponents. 

nice

Thanks! I worked relatively hard on this idea!

Oh yeah... I remember why this 3D game wasn't as good as the others now.

Actually, don't touch Bowser in the main Super Mario games. Different antagonists in Mario RPG games and the rest is OK.

*EDIT: Oh I get the point of the thread. My bad! I thought you meant replace Bowser for a new antagonist. @_@

Fawful for main antagonist. I HAVE FURY!!!!!

Sounds good and I would like to see the return of the seven bowser's children in the next mario game.

The story could be something like this :

Iggy & Co. are tired to see their father be beated by mario each time. So they decide to take the throne and jailed bowser. After they contact peach and say that bowser has move from the mushroom kingdom to another kingdom. Happy to hear that , Peach and mario make mario party 9 ( because they think that the children of bowser are too coward to attack the mushroom kingdom ) And then BAM the mushroom kingdom is attack and mario and luigi need to save their home.

I'd like to see a Mario game where Wario's the bad guy again, like he was when he started out. And have him team up with Waluigi, too.

Wapeach, Wadaisy or Warosalina riding an evil Wayoshi.

I like the Koopalings making a return. I think the more baddies the better. I don't know about you but rebattling Bowser like 4-5 times in a single game gets pretty boring. I wanna battle multiple baddies. Should their be a new Antagonist? Yah that would be pretty cool If DK gets a new Tiki antagonist why can't Mario get a new antagonist.

That being said the Paper Mario games have introduced new Antagonists. Your idea is alright but I'd like to see what Miyamoto could come up with!

My wish.