Must... resist.. urge to kill!
Krillen has been in this many battles that I know of in DBZ:
Krillen Vs 4 Saibamen
Krillen Vs Nappa
Krillen Vs Vegeta
Krillen Vs Ginyu No. 1 (Weird Four Eyed Guy)
Krillen Vs Ginyu No. 2 (Big Guy)
Krillen Vs Freeza
Krillen Vs Cell Form 1 (It was short but he lived through it)
Krillen Vs Cell Form 3 (Shorter but he still survived)
Krillen Vs Buu (Shortest Battle in history of DBZ
)
Tien has been in this many battles that I know of in DBZ:
Tien Vs 1 Saibaman
Tien Vs Nappa
Tien Vs Two Ginyus (Cant remember their names)
Tien Vs Cell (Pretty short)
Tien Vs Buu (I've never seen this one but I've only seen up to Gohan going Mystic.)
Lets look at the list and see whos been in more battles... Amazing, its Krillen. :\
OK, so I'm being sarcastic but you get my point...
P.S I don't think theres much chance of any new characters soon, considering their building Custom Chars as well.