All rings:
At the Title screen, press C-Left, L, C-Right, R, C-Left, L, C-Right, R, Z. A ton of new rings will be playable. You'll hear a sound to confirm proper entry.

Ring select:
At the Options screen, press C-Right, R, C-Right, R, Z. You'll hear a sound to confirm proper entry. Press Z to advance through the rings.

Unlock set of wrestlers:
At the Title screen, press R, L, C-Right, C-Left, C-Left, C-Right, L, R, Z. You'll hear a sound to confirm proper entry. Now highlight a wrestler at the Character Selection screen and press C-Left, C-Right, L, R, C-Left, C-Right, L, R, Z. Now all three hidden wrestlers related to that wrestler will be unlocked.

Swelling heads:
At the Title screen, press C-Left 7 times, L, Z. You'll hear a sound to confirm proper entry.

Big head mode:
At the Title screen, press C-Right 7 times, R, Z. You'll hear a sound to confirm proper entry.

Big heads, hands, feet:
At the Title screen, press R 7 times, C-Right, Z. You'll hear a sound to confirm proper entry.

Big hands:
At the Mode Selection screen, press L 7 times, C-Left 17 times.

Call for backup:
During a match, press Z for another wrestler to enter the ring and interfere with the match.

GameShark Codes

Infinite Health P1		8122915203e8	
No Health P1			812291520000	
Infinite Health P2		812296ba03e8	
No Health P2			812296ba0000	
Infinite Health P3		81229c2203e8	
No Health P3			81229c220000	
Infinite Health P4		8122a18a03e8	
No Health P4			8122a18a0000	
Infinite Time Out of Ring P1	812291aa0000	
Infinite Time Out of Ring P2	812297120000	
Infinite Time Out of Ring P3	81229c7a0000	
Infinite Time Out of Ring P4	8122a1e20000	

Brian Adams		8027d81d0001	
Bulldog			8027d81f0001	
Booker T		8027d8210001	
Dean Makenko		8027d8230001	
Wrath			8027d8250001	
Ultimo Dragon		8027d8270001	
Kidman			8027d8290001	
Disciple		8027d82b0001	
Chris Benoit		8027d82d0001	
Scott Norton		8027d82f0001	
Konnan			8027d8310001	
Anvil			8027d8330001	
Roddy Piper		8027d8350001	
Buff Bagwell		8027d8370001	
Kanyon			8027d8390001	

Alex Wright		8027d83b0001	
Eddy Guerrero		8027d83d0001	
Hammer			8027d83f0001	
Stevie Ray		8027d8410001	
Scotty Riggs		8027d8430001	
Horace			8027d8450001	
Rey Mysterio Jr.	8027d8470001	
Lodi			8027d8490001	
Sickboy			8027d84b0001	
Disco Inferno		8027d84d0001	
Ernest Miller		8027d84f0001	
Barbarian		8027d8510001	
Meng			8027d8530001	
Fit Finley		8027d8550001	
Reese			8027d8570001	
Chavo Jr.		8027d8590001	
La Parka		8027d85b0001	
Eric Bischoff		8027d85d0001	
Mean Gene		8027d85f0001	
Miss Elizabeth		8027d8610001	
Arn Anderson		8027d8630001	
Bobby Heenan		8027d8650001	
Kimberly		8027d8670001	
Larry Zbysko		8027d8690001	
Sonny Onoo		8027d86b0001	
Mongo			8027d86d0001	
Kaz Hayashi		8027d86f0001	
Jimmy Hart		8027d8710001	
Rick Rude		8027d8730001	
Enos			8027d8750001	
Psychosis		8027d8770001	
Juventud Guerrera	8027d8790001	
Rick Fuller		8027d87b0001	
Zoomie			8027d87d0001	
Jamie The Learned	8027d87f0001	
Stingray		8027d8810001	
Cobra			8027d8830001	
Reanimator		8027d8850001	
Sleep Dep Ed		8027d8870001	
5 O'clock Tony		8027d8890001	
Uncle Monkey		8027d88b0001	
Dudeman			8027d88d0001	
John			8027d88f0001	
Chicken Boy		8027d8910001		
Dynamite Johnny		8027d8930001	
Benji			8027d8950001	
Wrestling Matt		8027d8970001	
Goochie			8027d8990001	
Devastatomg Dorizas	8027d89b0001	
Veal			8027d89d0001	
Miri Myque		8027d89f0001	
Spice			8027d8a10001	
Whisper			8027d8a30001	
Tiger			8027d8a50001	
Fyre			8027d8a70001	
A.C. Jazz		8027d8a90001	
Chae			8027d8ab0001	

Thanks to Revolution readers Tony, Kyle Allen, Mike Steinbruegge, Jordan Payne, Mike Mackey, Zac Boyer, Calen Mitchell, Robert Bowen, Michael Zielinski, Grant Nuttelmann, Tony Howland, and Jesse Wityczak!