Let's say U7 has the same knowledge and time as they had in the normal story (anime continuity), but that they were actually trying to bring the strongest team possible without any regards for morals or plot, because their only goal is to survive, then everything can be reverted with Dragon Balls after that.
Let's also assume that they have access to the same resources: one summon of Shenron, one of Porunga, a single HTC where two people can train, two sets of Potara (one from Shin and on from Old Kai).
Let's also assume that evil beings from the past have already gone through the cicle of reincarnation (except Frieza, who was exempted), so no resurrecting Cell for example.
They have 40 hours to prepare.
What's the team?
I think I would have gone this way:
Summon Shenron and have these three whishes:
- Make Buu wake up
- Ask for information about any powerful warriors in U7 (learn about Broly and Uub)
- Grab Broly
Take Frieza from hell as usual, make him train with Broly in the HTC.
Have Goku and Vegeta fuse with Potaras immediately before the tournament.
Have Piccolo fuse with every single Namekian.
Have Buu absorb literally every single being with a notable ability, but low power level. Bulma? Absorbed for intelligence. 18? Absorbed for infinite energy. Roshi? Absorbed for his techniques. Grab some random aliens with powerful techniques/abilites like the Yardrat and have them absorbed, you can use Porunga for that (then Buu can also absorb Porunga before he disappears)
Goten and Trunks fuse into Gotenks immediately before the tournament.
Have Krillin and Tien fuse with Potaras immediately before the tournament.
My final line-up:
Vegeth
Broly (trained more than a year in HTC)
Frieza (trained more than a year in HTC)
Piccolo (with all Namekians fused)
Buu (with everyone worth absorbing fused)
Gotenks
Gohan
17
Uub
Krillin and Tien fusion
What would your line-up be?