To unlock Black Widow (a female wrestler), you need to win the World Cruiserweight Championship from the Whole World Wrestling league challenge (needs to be unlocked first).
Diamond Dallas Page
Beat WCW Challenge Mode.
Glacier
To unlock Glacier,you must win any belt from the Independent Union.
Joe Bruiser
To unlock Joe Bruiser, you need to win the World Heavyweight Championship from the Whole World Wrestling league challenge (needs to be unlocked first). Joe Bruiser is a boxer that can't grapple and can't put the opponent back on the feet when he's down. But he has very strong punches.
Rip the masks off!
To rip off the masks of any of the masked superstars in the game like Rey Jr., Hannibal, or Black Ninja, repeatedly press by the head of the wrestler when he's on his stomach or on his back to do the eye gauge or camel clutch submission holds, keep on doing this several times and you'll finally see the wrestler's face!
Wrath
Defeat the heavyweight or cruiserweight league challenge for the DOA.
WWW/Whole World Wrestling league challenge
To unlock the WWW, you need to complete at least one championship in every league (WCW, NWO, DOA and IU).
"Macho Man" Randy Savage...