As we all know, there is a ton of mystery surrounding the "End of GT" era of Dragon Ball. One of the few things Goku said before he left was to tell Vegeta that he was now the leader of the Dragon Ball Gang (A.K.A. Earth's Special Forces). With the info I have, I've theorized who'd be on the team and why they'd be there. If anyone is excluded that you're confused about, I can explain in the comments! Anyways, here we go: (Gonna go from upper left to bottom right)

Gohan: While not the fighter he used to be, Gohan would still be a great fighter to have on Earth's Special Forces because A), he still trains on and off, and B), I'm almost positive that the likelihood of another threat as big as the Shadow Dragons wouldn't emerge again, so he'd be useful once again.

Chiaotzu: Yes, yes, yes. I know, you're probably thinking "Why him? This is GT, not OG." However, Chiaotzu has been training with Tien for the entirety of GT so a great boost in power should be most likely what he's gotten. Not to mention that since he doesn't age, he'd be one of the longest lasting members age-wise. Plus, Chiaotzu needs some love.

Tien Shinhan: This one is a given for a guy who put Chiaotzu on the list. Tien was at a point where he could block attacks from Buutenks in the Buu Saga and push back Semi-Perfect Cell. While not the strongest of all the Earth's Special Forces, I still think he should be on simply for his relative power (which is arguably higher than Pan's, or maybe that's just my headcanon).

Mr. Satan: He's contributed to the Earth's Special Forces' efforts before in many unexpected ways. How he couldn't contribute at this point would be beyond me, to be frank.

Uub: Majuub would definitely be one of this team's top-tier fighters. The guy fought head-to-head with Baby, Super 17, Syn Shenron, etc. While he may not have won all said fights, his power in undeniably useful. Not to mention, he could hold up Goku's legacy as his apprentice in the process.

Gotenks: I say Gotenks because individually, Goten and Trunks are pretty good, though Gotenks is obviously better! He, too, would be a top-tier of the team, and naturally it makes sense that the sons of Vegeta and Goku would fight in the final incarnation of Earth's Special Forces, right?

Vegeta: Do I really even need to explain this one? Goku himself said before he left that he wanted Vegeta to protect Earth, so him being the leader of this group only makes sense, completely ignoring the fact that Vegeta would be a top-tier fighter on it as well.

Nuova Shenron: Probably the most confusing besides Chiaotzu, yes I know, but there was the possibility that Nuova was resurrected by the Dragon Balls once it was asked that everyone killed by Omega Shenron be revived. Technically speaking, Nuova'd been killed by Omega. If he was a member of the team, he'd be like Jiren: Not the leader but definitely the most powerful. At least for some time, as in if Vegeta or someone else surpassed him.

Pan: Well, duh. You knew she'd be here. She was a main character all the way throughout GT and her contributions were fruitful in their results. Plus, she'd have no reason to give up fighting considering she's the strongest kid around.

Giru: Powerful in his own right, he should be right around Nappa in power simply due to being a Machine Mutant. Not only would this help against really small threats, but he also acts as the Dragon Radar which is obviously a useful bit to be.

All THAT said, hope you enjoyed looking at 'em! Had fun going through and thinking about this. Took me awhile.