Tien is a good character, unfortunetly his power level didn't rise like the rest of the characters. You see dbz soon went from fighting skills to just who threw the bigger beam, much like in the game itself that when your pl goes up some people get big headed and go on making 400 kamehs that detonate hte entire map going "Haha! I pwned you! n00bs!"
It's rather sad, but most people nowadays like to be "I WANT TO STAND OUT AND BE STRONGER THAN YOU!" . Strength isn't really the powerlevel, it's the character of the.. well.. character? I would have to say Tenshinhan is a great character, he is depthful and isn't static. In the show though and I'm taking in the game as well, it was just who had the higher powerlevels that kept going on. Which would of course be the saiyans. The androids were powerful but they too disappeared, 18 disappeared even when she became a good guy. In GT it's disgusting, only chibi goku is the only strong protagonist. Gohan, Goten, even Vegeta all become weak old men as they get batted around by some random space guy going "I happened to stumble upon earth! bwahah! I shall destroy all you uber-n00bs!"
Back to subject.. ^^;;
If they do add new characters it's of course going to be powerful ones, as regretful as that is it's the powerlevel people nowadays only concern themselves about. "My pl is 5 million!" "Oh yeah? mine is 20 billion!". If you stripped them all of their pl's and they only relied on physical skills, I'd say Tenshinhan would of whooped them all. Well maybe not Goku but then again it was Goku's pl that kept him alive. He was dumb as a nail though XP. Wait.. what am I saying? He still is =)
All I know is, long live Gohan!