You are selected for the role of determining U7's lineup for the ToP, this time around you are able to call forth any fighter from U7 dead or alive (canon or not). Additionally, you can call on fighters from alternate timelines within U7 such as Future Trunks or Gohan. However, you cannot call on two of the same fighters from different timelines such as Post GT Goku and DBS Goku meaning you either choose Post GT Goku who trained with Shenron for a 100 years and is able to go SSJ4, but is not able to go SSGSS.

Also, for arguments sake assume that SSJ4 = SSGSS and DBS Goku does not have UI unlocked.

I would go with the following guys:

Post GT Goku: I know this one might be a shocker but my reasoning behind this is that he would be much stronger and wiser after training with Shenron for 100 years. Of course, his love for battle is still the same but as a SSJ4 (his best form in this timeline) he is a much more serious character. This would be key in a winner takes all tournament because I feel his newfound wisdom and knowledge coupled with a serious attitude would benefit in a team setting.

Post GT Vegeta: Same reasoning as above, BUT it would be amazing to see a return of SSJ4 Gogeta.

Future Gohan: Even though he might be weaker than DBS/DBZ Gohan, Future Gohan is one of my personal favorites because he is much different than regular timeline Gohan. Future Gohan is much more battle hardened and serious, he saw his whole family and everyone he cares about die at the hands of the Androids and giving him another chance to avenge his Universe by competing in the ToP would certainly motivate him to go above and beyond his limitations (He is a Saiyan after all and they improve through Battle).

Future Trunks: See above.

GT/Teen Goten: One of the only reasons I would bring Goten along in his teen form is for the ability to fuse with Future Trunks and produce an adult version of Gotenks (see DB Heros).

Majuub: Uub and Buu fusion would be a really strong competitor and provide good depth to the team. Chocolate Kamehameha would be awesome to see in the ToP as well.

Piccolo: All around great choice, fighting alongside Future Gohan and Adult Gotenks would be awesome.

Pikkon: One of the strongest fighters of the west quadrant of U7 and because I would love to see a fusion between him and Piccolo.

Android 17 & 18: Unlimited energy, strong team players, great additions.

I know this probably isn't the best team, but I think it would be kinda cool cause of all the fusions and different styles/timelines interacting. Lemme know who you guys would choose!