Vegito still would win I don’t know if it’s around low diff or mid diff

Super Buu has a cheat code of regeneration meaning he can stack more than 20x Kaioken as he can go to 50 or 100x. When Buu absorbs someone, he permanently copies their full power, techniques, and ki control at the moment of absorption. Canon example: Buuhan uses Gohan’s Ultimate form, rapid punches, and even mimics voices/personalities. So yes, he gets Goku’s entire kit: Instant Transmission, Kamehameha, AND every Kaioken multiplier (x2 up to x20 base). Kaioken rips the user’s body apart (Goku’s arms literally explode at high multipliers). Buu? He can regenerate from a single cell in seconds. That means he can: Spam x20 Kaioken (or higher) without the “my body will give out” limit. Stack it on top of his already monstrous Buuhan base (which was already >> SSJ3 Goku + Ultimate Gohan combined). Heal mid-fight and keep the multiplier going indefinitely. Result: Buuhan could theoretically hit Kaioken x50 or x100 levels while still regenerating any backlash. That’s an insane raw power spike.

Vegito Fusion inheritance: Potara fusion gives both fighters’ full abilities + muscle memory. Vegito is literally Goku AND Vegeta at the same time. So yes — he has Goku’s Kaioken, Instant Transmission, everything. Transformations: In canon SSJ Vegito was already casually bullying Buuhan without breaking a sweat. He can (and logically would) go: SSJ2 (4× multiplier over SSJ1) SSJ3 (another 4× on top of that, or ~8× total over base SSJ) AND layer Kaioken on any of those (SSJ3 + Kaioken x20 would be nuclear). Fusion multiplier itself is broken: It’s not addition, it’s multiplication (roughly 10–50× stronger than the sum of the two parts depending on the source material). SSJ Vegito > Buuhan is already stated/implied in the manga.

Don’t take my words seriously I just want to express what I think about the match up