No you're a little wrong. The dance requires both fighters to have an almost equal P. Level. Potara combines their max levels. Goku told Trunks to lower his P. Level to make it closer to Goten.
Gender: Male Location: Khonaha Village
Dragonworld
Anti-
Ouch this is hard, we never really see what Janemba can do when he gets realy angry, since he only ever fought someone alot weaker >>goku/vegeta or alot stronger>>, Gogeta, he DID warp all of Reality..just by existing...has mass reality warping matter manipulation powers and has powers beyond those of even a SSJ3, Then Again Buu absorbed Gohan nearly destroyed the Universe with his power, and is alot smarter, id love to see this fight they are the 2 most powerfu villians eve seen in DBZ...what a fight ..
Super Buuhan easily. Goku was being beaten by Janemba, but he was still holding his own. Super Buu alone was said to be too much for Goku and Vegeta combined, and it was implicated repeatedly that Goku could have beaten Fat Buu, but that Super would annihilate him.
That's just Super Buu. Super Buu with Gohan absorbed will crap all over Janemba. Janemba's one chance would be to open up a portal as Super Buu does his candy beam and send it back in his face. If Janemba could eat the candy then maybe they'd fuse and we'd get Janembuu...
No, combined, as in "fighting together". This was said by Goku while they were in Super Buu and Vegeta had crushed the portara.
Even after rescuing their kids and Piccolo, they still felt he was too strong as regular Super Buu and Goku says "If we go out there, he'll kill us.", so they found Mr Buu and cut him loose resulting in Super Buu reverting to Kid Buu who was weaker, and Goku and Vegeta were eager to fight him on even terms after that. Of course, Kid Buu is just insane and pretty much blew up the planet straight away...
Gohan was the only non fused person who could take on Super Buu, unless you count anime filler that contradicts what was stated repeatedly.
Goku performed pretty well against Janemba, until he whipped out that sword, and his ability to phase and redirect attacks was helping him. Obviously Janemba was stronger than Goku, but I think Goku would have had a lot harder fight against Super Buu, let alone, Ultimate Super Buu.
I think:
Vegitto and Gogeta > Ultimate Super Buu > Super Buu with Gotenks and Piccolo absorbed > Mystic Gohan > Super Buu=SSJ3 Gotenks > Janemba > Kid Buu=SSJ3 Goku=Original Fat Buu=SSJ1 Gotenks > Evil Buu > Gotenks > Mr Buu=SJJ2 Vegeta > SSJ2 Gohan