Goten was in the series at the very end, and he really didnt do anything. The writers fudged when they though him up, thats for sure. Why is Goku's 2nd son stronger than his first? Having him trans as however old a kid he was is just stupid. Gohan didnt, and he even had that hidden power thing.
As for Gotenks, well, you might as well just add Vegitto. He was at least a fusion of two fighters, not just a couple kids fresh from the sandbox. But Id rather that fusions dont end up in ESF.
Personally, Id have to vote for Brolly. I know that ESF is a DBZ mod, to the exclusion of the movies, but Brolly was just cool. I think ESF has enough saiyans, though.
Bring on that Ginyu team and the androids!