There are a lot of options but all of the Earthlings feel underwhelming compared to the scale of the Tournament of Power, besides #16 who should still be lying somewhere in Gero's laboratory, but the question is if Trunks can find him (and if he's willing to work together with an artificial human)? We don't know what Shin (remember that in the new timeline he was saved by Whis and Beerus) did with Boo's cocoon, but presumably it was left on Earth or taken with Shin to the Kaioshin Realm. Mai and Chi-Chi could be considered, as well. Elsewhere, Penguin Village's inhabitants would be powerhouses if they still share the same world. Baba's fighters could be useful, considering the invisible man's and Akkuman's powers. Satan and Videl are options, as well as some of the stronger ones such as Chappa and Namu. Weaker Tenkaichi Budokai participants such as Spopovich, Yamu, Panputt, Giran Mr. The likes of Tsuru-sennin and Tao Pai Pai could still be alive. From the fighters left on Earth, he'd have to pick from (presumably) Kame-sennin, Yajirobe, #8, Karin, Mr. Trunks, of course, would be a given, maybe even the two that now reside within the same timeline. But suppose the Omni-King or the Grand Priest come up with the Tournament of Power idea independently and decide to hold it following the same rules as the one in the main timeline. The Tournament of Power would likely never happen in Trunks' timeline, considering the U6 invitational tournament never happened to excite the Omni-King about martial arts, and the second Omni-King doesn't exist to remind the first of his promise to uphold a new tournament.