Does anyone know through screenshots / videos if they shown any of the bosses from New Super Mario Bros. U?

No, but I imagine they will at the September 13 conference.

Probably will just be the Koopalings...again anyway.

Recently the NSMB series has lack of original bosses. The first game on DS had variety. Bowser, a grey pokey, a giant goomba, Petey Piranha, a lightning Lakitu just to name a few. NSMB Wii had Koopalings for towers and castles, which is understandable as they weren't featured in any game for a few years. NSMB 2 had Reznors for towers and Koopalings for castles. The Reznor fights can't really be varied too much, then again most fortress/tower bosses in Mario games are just the same thing with minor differences ( a big problem with 3D Lands bosses). The Koopaling fights were half new and half old. See Iggys fight, it's nearly the same as his castle fight in NSMB Wii. I really hope this game has more variety in it's bosses.

I think they should go back to unique bosses in this game. Now that they brought back Koopalings and the Reznor, they could bring back Boom-Boom into a 2D game for the tower levels.

There's no info on the bosses in the game or the story in general.

I'm hoping for some new bosses or at least something that differ from the current Koopa Kids. NSMB2 and NSMBW essentially has the same bosses with the same boss-patterns. That's boring.

Hopefully the more experienced Mario team will come up with something more fun.

I like petey piranha! His fights are always fun. :3

I like how the better games in the series didnt recycle bosses. Here's an idea Nintendo - instead of trying to recycle the enjoyment people had from Super Mario Bros. 3 - why dont you just create a new game from scratch? Yoshi's Island had the best bosses for the record (No that doesnt mean the next game should use the same bosses - that would be stupid).

Since the more experienced 2D Mario developers are working on this game and how different it looks compared to the past NSMB games, unique bosses should be likely. But, I'll mention again that the September 13 conference should reveal them.

My thoughts:
Towers- Koopalings

Castles-
1 Petey Pirahna (Grass world)
2 Squirrelapilla (Forest World?)
3 Creepatree (Spooky World?)
4 Big Bad Blubberpus (Ocean?)
5 Venom Koopa (Poison?)
6 Elemental Lakitu Crew (Sky?)
7 NSMB2's Reznor fights followed by Colossal Sand Rex (Desert?)
8 Bowser (Volcano)
9 Goomba Toy Train (Toy World???)
10 Koopalings in Clown Car (Mountain World?)
(Tower: Bowser Jr. in mini clown car)
11 Robo Bowser
(No Tower Battle, just tower.)
12 Metal Bowser (Dark Void World)
(Tower: A race against Bowser)
World ☆ (Rainbow World)
Every level has a different koopaling battle.
Final has Dark Bowser (Remixed theme from M&L BIS!)
Unfortunately there will probably only be 8 + 1 (bonus) worlds, so booooo...

No dark bowser. He was an rpg character. But if we are throwing around rpg characters, then GEEEEEEEEEEEEEEENOOOOOOOOOOO!

Anything but Boom Boom please. He has to be the most annoying and the worst idea for a mini boss in a mario game EVER. At least, that's how I felt in SM3DL for facing him over and over again.

That was 3D Lands big problem. Every Airship boss was either Boom Boom or Pom Pom with small arena variants like spikes or flames. Even the Bowser fights only had different bridge designs.

Boom Boom and Pom Pom Alone made me quit SM3DL, so hopefully they don't put them back here.

You wouldn't like SMB3, then, since you would fight him a dozen times and he could be beaten without even giving him a chance to attack every time. Still, at least the Koopalings were new at the time and made up for the seemingly repetitive Boom-Boom fights. NSMBU could be the same way by having new bosses to fight along with a Boom-Boom skirmish now and then.

I see nothing wrong with bringing back the Koopalings. Just, they don't need to rely on the SMB3 mechanics for them. I think the Iggy fights with the chain chomps are a step in the right direction, but generally speaking, they could take a page from the Iggy/Larry SMW fights and have something with a challenge that is not the usual "jump on them three times".

I would like to see Pom-Pom in a 2D game though.

I actually don't like SMB3 a lot. Only SMA4.

You know what would be cool? Bosses where you did something other than jumping on their heads three times. Maybe there could be a boss that can only be beaten using power-ups, or more Yoshi's Island style bosses.

Needs Birdo, Mouser, Fryguy, and Triclyde. And Wart as a surprise World 8 next-to-final or final boss! It would be amazing to expect Bowser for the umpteenth time, only to find that Wart got out of Subcon and is pulling Bowser's strings somehow (or they teamed up)!

Won't happen, as SMB 2 USA is the black sheep of the SMB series (1988 was THE year for black sheep, see: Zelda II), but it would be a heckuva surprise! Wart turned Giga Wart by Kamek could be a pretty terrifying final boss (especially in HD)!

At any rate, I'm really excited for NSMB U. You have to figure it'll be better than NSMB 2, and it's proving to be my favorite of the NSMB series! Side-scrolling Mario at launch one again is like a retro gamer's dream come true!

I think that if NSMB2 has taught us anything - it's that Renzor is the worst miniboss ever. The boss level is less creative than Boom Boom and having it on every world was just cheap. Most boring battle ever... Sure he might be fine to battle once, and your love for SMW may blind you to the truth - but c'mon, those battles were horrible.