Tien- he was basically a guy that ripped up Nappas armor a little bit and got his hand cut off, he could also grow 4 arms.
Krillin- after he was killed by Frieza he was pretty much done he really never did much to speak of.
Yamcha- not much to say here, he was killed in the show twice and both of his deaths were retarded oen by the stupid green cyba men and another by an android sucking out his energy.
Piccolo- stayed pretty constantly throughout the show, he had plenty of glory moments, the perfect backup character for any show.
The show really drifted away into the Saiyans becoming the only ones who could fight. Goku, Gohan, Vegeta, Trunks.