The following wrestlers can be unlocked if you complete some certain aspects of the game.

Wrestler	How to unlock
Andre The Giant	Win 92 matches.
Bam Bam Bigelow	Win 56 matches.
Big Boss Man	Win 38 matches.
Big Show'00	Complete a triple threat match 40 times.
Billy Gunn	Complete tag team math 35 times.
Booker T	Win 70 matches.
Brett Hart	Win 90 matches.
Brian Pillman	Win 44 matches.
Wcw Flyin'brian attire	Use the springboard dive 20 times.