At the arena select screen in VS. mode, hold the Z button on Basic Arena or No Man's Land to play with alternate graphics for those stages.
Completion Bonuses
To unlock Arcade Mode, First Person View, Parts Index, and The Grand Battle in Single, and Versus Mode CPUs, you must complete 'A New Journey' mode in single player.
Parts Index
Beat a new journey in story mode.
Ray Legend
Get a gold trophy in all cups in the Z headquarters then talk to Oboro.
Ray Warrior
Get a gold trophy in all the cups in the Amusement Park, then talk to the policeman at the front gate.
Fresh Stage
Go to VS mode highlight the basic arena or No Man’s Land and press Z.
RahuIII
After you Beat Grand Battle Mode, go back to the 'Outside world' Amusment park. Enter the Silver Battle Royal and do not skip the senario. Before the match starts walk straight down until you find a broken carriage. You can enter the carriage on the right side. Inside tap A like crazy till you pick up a data chip. And now you have big, bad Rahu3.
Link Bonuses
Use a Game Boy Advance link cable to connect to Custom Robo GX to unlock the Dark Core stage and new Robo parts in the Japanese version of the games.
Dark Star versus mode stage
Play versus mode 50 times with any one Robo. For example, play vs. mode 50 times with Ray01.
Athena
After completing the Bronze Handicap Match and getting all the silver trophies, not including the bronze handicap match, you will be able to compete in the Silver Battle Royal. You will not get any new parts for any of the matches except for the last one. Once you finish the last battle, you will get the Athena body part.
Cans
To get "Can Robo" Can Bomb, Can Pods, Can Boots, and Can Gun, win the Tournament in your house. You can now enter Lucy's room. In there you will see lots of people talking about what they did for the game (similar to "talking" credits). Go through the second door and you will see more people. In the second room there is a robot (not a Custom Robo). Talk to him after he is done talking. The game will save. Go to the nearest parts generator and get ready to laugh at what you just unlocked.
Chickenheart
In the Z Boss battle, look on the north side of the west pillar.
Crystal Strike
Defeat the fourth CPU in in the Test Center, then keep talking to it until you get the Crystal Strike gun.
Rakansen
Win all the Amusement Park Tournaments with bronze trophies.