Based on these comments, I'm thinking Kirby won.

Screw Attack clearly has a bias against DBZ. They had Superman beat Goku....by using retconned OP Superman abilities vs. flawed mathematics based on the very first DBZ saga. And now they apparently have Kirby beating Buu. Dude, Buu could just nuke the planet Kirby is on then move on to the next one. In fact, that's something he *would* do (he did it against Goku and Vegeta). Or just turn Kirby to chocolate. So unless Kirby has teleportation powers to avoid a planet bomb or can just deflect magic to prevent him from being turned to food, then this is just another screwed up Death Battle.

Unless, of course, Buu won. Then I'll happily stfu

Well, if he can drive a machine that travels in light speed, he must have light speed reflexes himself. Like the video pointed, he can be insanely powerful.

The problems with this battle is that logic is very different in Kirby cartoon. In one episode he struggles to push a block, while in the other he break the world in half or fight both the Sun and Moon, and win.

That said, once you decide you will make a "death battle", you need to use the greatest parameters to define their power limit. So Kirby is in the end an indestructible cosmic eldritch aberration that can move in the speed of light, throw giant monsters in the sun at match 73 speed, break planets with his fists and has a whole universe in his belly.

He just choose to not use the full extend of those powers or don't know how to use them full time.

Majin Buu wouldn't do that. Besides Post Crisis Superman benched pressed a planet for 5 days without sunlight. And Kirby is faster than light with the warp star. And ScrewAttack would have Vegeta lose against Shadow if they were biased. Besides, they're good friends with Team 4 Star, and even got sponsered by Funimation. If they were sponsored by Funimation, that would make them biased for Dragon Ball.

The video points out some facts about what you said.

1- When Buu destroyed the planet he was in, his body was teared apart and regenerated after. When a planet Kirby was in exploded, kirby didn't had 1 single scrath.

I also almost sure Kirby can live in space like Buu or Frieza. So exploding his planet would not kill him.

They had Vegeta beat Shadow so there's that!

Also it was obvious to me that Kirby would win and how even before watching cause you know, Kirby: Right back atcha! He'll just take your strongest atk and chuck it back into your face!

He has an infinite air supply in his endless stomach and his body is clearly strong enough to withstand any amount of pressure so be it the depths of the ocean or outer space Kirby can survive!

https://www.youtube.com/watch?v=WW3zD5QoL74

wut? And Buu can move at light speed. He must have learned instant transmission or something in order to get to the Kai world (it's on a different plane). And Post-Crisis Superman had his power reduced. He can't move planets anymore. And I'm sorry, but if Vegeta (or anyone from DBZ with any sort of competency. So no Chaotzu or Master Roshi) lost to a damned hedgehog, Death Battle would have to be cancelled for such heresy =/. Vegeta should have just Big Bang Attacked Shadow and had the battle be done with instantly.

Also, Buu could just absorb Kirby. Dunno why they had Buu suck up some rando, while letting Kirby suck up Buu. Also, they got it right about Buu being about to break dimensions (since that is what happens when Kirby absorbs you), but when Buu absorbs you, you're just stuck in his stomach, unconscious. Why didn't Death Battle show this? Why'd they have Kirby dodging attacks that happen at light speed? Kirby can move at light speed? Only on his star. They had Kirby dodging energy attacks by getting googly eyed and dodging. 

No... they shouldn't use the greatest parameters, they should use the character's typical abilities.  There is no consistency in Kirby's warp star travelling at the speed of light, there is no consistency in him being able to throw things at mach 73 (it's a sight gag), and I'm not sure where they got the "univers in his belly" thing.  He could store like... five things in Squeak Squad.

Except for a few random moments in the anime (which is inconsistent) Kirby's not portrayed as being that strong.  Meanwhile, Buu can destroy planets without really trying too hard (Kirby could crack them at max power, and even that is just one minigame), and is virtually indestructable (Kirby is hurt by anything pointy).  

Facepalm. I never said Superman could move planets. And NONE OF BUU'S ATTACKS HAPPEN AT LIGHTSPEED! BUU WANTED TO KILL KIRBY, NOT ABSORB HIM! Ugh, why can't you just accept that Buu lost? And to the guy above me, all feats are inconsistent. You wouldn't nerf Shulk just becuase you don't always see him reset universes, do you?

I refuse to believe that kirby would even scratch Buu, much like super beating goku. Entertaining nonetheless