I think it's amusing that so many jump to say, "Toriyama was lazy, DBZ has plot-holes," What is the reason behind insulting a show, whose forums about a game based on the series,on which you spend time posting in?
In other words, there's no reason to insult Toriyama Akira for not including irrelevant storyline about Trunks and Goten's tail. It's too bad if you wanted info about it, and it's not there--but it's not a reason to insult the show.
They also didn't include pointless storyline such as 'Goten's first haircut,' and 'Trunks first homosexual experience.' Get the point?
Maybe they'd shown enough of the tails. Also note the senshi never use Tayioken(solarflare) on Majin Buu. They must've FORGOTTEN about it. Toriyama must've gotten LAZY! Because you know, if you don't see something in a later season, it's pure LAZINESS!