Successfully complete "A New Journey" mode in single player to unlock Arcade mode, first person view, parts index, and The Grand Battle in single player, and Versus mode CPUs.
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.
Defeat Rahu 3 at the end of the game to unlock first person view. You can keep this off, however turning it on does not automatically make you see in first person view. When you get into battle with this option on, you can switch in-between the two views by pressing C-stick Up or switch back to third-person view by pressing C-stick Down.
Select versus mode, then highlight Basic Arena or No Man's Land and press Z to change their appearance.
Select versus mode then choose three matches. Finish the three matches and a new stage will be unlocked.
Play versus mode 50 times with any one Robo to unlock the Dark Star versus mode stage. For example, play vs. mode 50 times with Ray01.
Successfully complete the game in story mode to unlock Versus battle CPUs.
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 (illegal).
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.
In the Z Boss battle, look on the north side of the west pillar.
Defeat the fourth CPU in in the Test Center, then keep talking to it until you get the Crystal Strike gun.
Win all the cups in the Z Headquarters tournaments with a gold trophy, then talk to Oboro. Also in Grand Battle (Episode 2), after winning every tournament in the city you will have access to the Outer World. When there, go to the Z Museum and defeat everyone to be able to go to the Z Boss Room. Once there, get a gold trophy to get the Ray Legend. Additionally, when you get to the Z boss room, you will fight (in order), Shiner, Eliza, Izabella, Oboro, then your host, Sensei. Sensei will then introduce your sixth opponent (the special guest), who is a simulation of Hero's father, the first leader and founder of the Z syndicate. He will say that his Robo is obsolete, and the Robo he is using is actually the Ray Legend Robo. It has a much stronger attack and much weaker defense than Ray 01, and will be easy to defeat if you can avoid him and knock him down. Try using all of Rahu 1 but replace his gun with the vertical gun.
Win all the cups in the Amusement Park tournaments with a gold trophy, then talk to the policeman at the front gate.
To get the first set of parts, go to the Z Headquarters, talk to Oboro, and select Eliza's Mansion. Go in between the glass and the wall, go all the way to the left, then up, then right. You will be in the glass case. Press A to find Rahu 1's parts and the Rahu 1 chip. Do the Bronze handicap match. When Lucy appears to fight, talk to her until you get Rahu 2's parts. To get Rahu 3's parts, go the Amusement Park. Do the Silver free for all battle. Go down and into the carriage near the merry-go-round. Press A to find Rahu 3's parts.
Go to the Lab Handicap battle, then press A against the books. You will get the Wave Laser gun illegal part.
To find the X Laser (illegal part), in a Grand Battle mode, go to Bogey's Café. Walk behind the counter and select the shelf. You will now have an illegal part.
Every Robo has a dash attack that they can perform with . Some Robos have a straight-forward dash. If you are using one of those Robos, keep pressing X and you will juggle your opponent and do a good amount of damage. This is very useful if you have low health.
To get illegal parts, complete the first seventeen tournaments in the Grand Battle section of story mode. In the Other World, when you complete the first three Z tournaments, you will receive no parts. However, all the battles in Z headquarters after those will reward you with illegal parts, such as the Wyrm, Wolf Spider, Orca, Cheetah, Swallow, Raven, and Eclipse. Note: The first parts you will receive are legs, but you will soon get the Wyrm, which is the advanced version of the Dragon (very powerful).
To get gold in a single use tournament, do not use Illegal parts as they cut your points in half. Use the following combination, or something of the sort. In the first two to three battles use Metal Ape, Metal Bear, Metal Ox, with these guns: Afterburner (stand back and fire for an easy perfect), Blade (stand back, fire your opponent into a wall, and keep firing for an easy perfect), Halo (stand on ground and fire repeatedly for an perfect). Note: These guns do not too well in Ice Holloseums, In the case of Ice Holloseums, use a Javelin or Halberd type. In battles four through six, use the Peregrine and either Shotgun or Knuckle. Note: If there are more battles than six, use Peregrine and Knuckle, Swift and Shotgun, And Shrike and Flame. For the last battle, use your preferred Robo (for example, Ray 01) and your favorite weapon (probably the Dragon).
Go to the bottom-left hand corner of the Holosseum. You should find data on the Holosseum.
To defeat enemies such as the Metal Bear, Tank Head, etc., use the Peregrine with Formula Legs and either the Shotgun or the Knuckle. You must get close to your enemies to use these weapons, but the Peregrine is incredibly fast, and the Knuckle and The Shotgun are two of the game's most powerful guns.
When the weird robot attacks Bogey's Café, defeat it then the blue-haired person. When Harry asks if you are going home, tell him that you will wander around. Then go to Hero's home talk to Lucy (the woman that sweeps with the broom), You will tell her about Z, and she will think that it is a band and that you were a security guard. Talk about the band. She used to hear the Groovy Goombas and their hit song "Fire Flower Sunshine".