DB Super: Hypothetical candidates for TOP

DB Super is building up to the Tournament of Power storyline but it seems the current conflict is simply finding suitable fighters. Who do you think, in the Z-Verse would make a good addition to Goku' team. My thoughts:

• Pikkon: I'm not sure if he's canon or not but he would be useful. Backstory: through off-screen training, his power could rank somewhere between SSJ2 and SSJ3.
• Frieza: Considering the universe is at stake. Fish Frieza out of Hell and dump him in the Time Chamber for a day so he can master his new powers. And then have Beerus supervise him just in case.
• Mystic Gohan: He is already a member. But is there a reason why he cannot undergo Elder Kai' ritual to unlock his potential again?

If fishing out Frieza out of hell is a possibility, why just don't do a better thing and revive Cell? He has both Saiyans' and Frieza's capabilities, so he can both (theoretically) reach Golden Frieza-like state and Super Saiyan-like states. He is already stronger than half the current team (exept for Buu, Gohan, Vegeta and Goku), and putting him into Time Room or whatever it's called even for 40 hours will seriously boost him. Plus with his proud warrior attitude he may not even be needed to be pressed into joining the tournament.

Or, if having him is too dangerous, you can just let him train in Time Room and set him up to be absorbed by Buu afterwards. So we have Buu with capabilities boosted by powers of upgraded Cell, more intelligence and all the powers of both Cell and Buu. AND there's the fact that Cell won't go rampant after the tournament if he will be absorbed by Buu. Win/win situation.

Golden Frieza & Golden Cell would be pretty awesome. A good contrast to the Goku/Vegeta dynamic.