The following are known Action Replay Codes for Ready 2 Rumble Boxing: Round 2 on Nintendo 64 (N64).

Device Compatibility: Action Replay & GameShark

Enable Extra Characters
80101e6f0003
80101e730003
80101e770003
80101e7b0003
80101e7f0003
80101e830003
80101e870003

Win 1 Fight to Complete Arcade Mode
80101f0b000b

Full Rumble Meter P1
d10ff6c20000
810ff6c20090

No Rumble Meter P1
810ff6c20000

Press L for More Time
d11121540020
810fe35215ff

Press R To End Round
d11121540010
810fe3520000