Alright, let's see here...
SSJ2FutureGohan wrote:SSJ3 Gogeta vs Super Boo (SSJ3 Gotenks absorbed)
Super Saiyan 2 is all Gogeta needs to have an easy fight and humiliate Boo
(though still not to the same extent as SS1 Vegetto). Super Saiyan 3 is overkill.
Kid Buu wrote:Bear Bandit Vs. Videl in her debut.
Before her training with Gohan, I doubt Videl has the raw physical prowess to take down Mr. Bear Bandit. AFTER her ki-training, though... that's a different story.
Angelus wrote:Tenshinhan VS Gohan
[Both Saiyan Saga. Tenshinhan will only do Tribeam barrages, like he did to Semi-Cell. Gohan will only tank and won't block. Who'll die first?]
I assume this is during the actual battle against Nappa and Vegeta, not before everyone trained. But either way, unless Gohan has some reason to be enraged towards Tenshinhan, he doesn't have the power to withstand a Kikoho. He either dies with the first one, or is left cripplingly injured and easily taken out with a second.
Since Tenshinhan starts this battle fresh instead of already half-dead, then unlike against Nappa, using the Kikoho doesn't kill him. It just leaves him worn out like after he used it against Goku.
Angelus wrote:Giant Culture Fluid Bio-Broly VS End of Z Giant Piccolo (like he did during the 23rd WMAT)
[No water nearby]
Piccolo's fond of using raw power to just eliminate the entire battlefield when the fight warrants it, and I believe that by the end of Z he's got more than enough power to take out Bio-Broli in such a way. The giant form probably isn't even needed in any way; heck, I'm not even sure if it's supposed to increase Piccolo's power at all.
Angelus wrote:Androids Saga Kamiccolo + Eastern Kaioshin Potara Fusion VS SSJ Gotenks (Post-ROSAT)
[No time limit]
Going by my favored, "more similar pairs make better Potara Fusions" theory... I don't think Piccolo and Kaioshin would get too much out of it. The difference in their powers isn't gigantic like between Goku and Mr. Satan or Dende, or something like that, but Kaioshin's still quite a bit stronger.
I'd say they get several times stronger, but don't quite match up to SS Gotenks in raw power. If the Fusion has inherited both his parts' special abilities, though, then they may be able to win anyway. I'll call this one a 50/50.
Angelus wrote:Cyborg Tao VS Drum
My gut tells me Tao
can win, but he'll have a hard time doing so. Nailing him with a Super Dodonpa may be required to do significant damage.
Angelus wrote:Full Power Beerus VS Buu Saga SSJ3 Vegito, Gohan-Buu, SSJ3 Gogeta, and Gotenks-Buu (no time limits)
No good way to know. The comparative scale between DBZ's "normal" heaviest hitters and the gods is impossible to know for sure. They don't even use the same type of ki.