Use the following to switch between characters in the middle of the game. For example if you choose Cable, Ryu, then Ken, but later in the second stage you want Ryu to appear first -- hold L1 for the second character and R1 for the third character at the versus screen.
The order of your fighters will appear before a versus match, with "1", "2", or "3". You can select the first and second fighters of your team, and thus change the entire team order. To select the first fighter, press LP + LK for the character marked "1", MP + MK for the character marked ''2'', or HP + HK for the character marked ''3''. Then, press the same button combos to select the second fighter. Press Start to continue.
Unlock every costume and character to chose multiple people. For example, player one could chose three Charlie's and the other player could also chose three Charlie's.
Exit and enter the shop screen until the price of the hidden fighters are lower.
To change the time of the clock in the background of the clock level, simply change the PlayStation 2's system time.
Press Start immediately after winning the match to move almost everywhere and have the ability to continue hitting the defeated character.
Select Gambit, Iron Man, and War Machine, then get a level 3 hyper combo gauge and do all their hyper combos (L1 + R1). It should do a 114-hit combo. If not, try starting the Hyper Combo with another person.
Note: This trick only works in training mode. Set the combo gauge to infinity in the training menu. Then, start a super and start another one. This can be done an unlimited amount of times. This works best with characters who have beam supers.
When your special meter is at 3 or higher, press L1 + R1 to do any character's special.
Choose Iron Man, War Machine, and Cable as your team, and make sure you choose projectile as their ability. Charge your super meter higher then 3, and press L1 + R1 (default for partner A and B actions). The result should be all three of your team members will use their projectile super move, which will take care of the opposition provided they do not block. Note: An advanced part of this trick is to wait until your opponent uses his partner in battle, then use the attack. The result is devastating.
Defeat Abyss with any time limit in arcade and score attack modes. His first stage will be unlocked in training and versus modes.
To defeat Abyss in his second form, choose Cable. Keep shooting Abyss with the pistol and keep shooting till you have level 1 on the gauge. Execute Cable's Hyper Viper Combo. This should kill him -- if not keep repeating this pattern. The works if you are fast enough to kill him while he performs his short range attacks.
Choose Megaman, Cable, and Cyclops. Play under the easy or medium difficulty setting. At Abyss, use Megaman then jump behind him and shoot. During his second form, use Megaman and continue shooting at him. You should have a level three power bar by now. At Abyss' third form, wait. He always dives down before attacking. When he reappears, do a Triple Hyper combo. If the game is set on very easy and high damage, Abyss should die in one hit.
You can get ten points a minute if you go to training mode, choose a character and opponent, then leave the game on for about five hours. Note: Do not pause the game.
Plug in a second controller, go to options, change the time to 30 seconds, and turn up the damage. Go to versus mode, turn the handicap down on controller two, and fight. You will get 100 points for each match.
To get easy points in arcade mode, fight up to Abyss in any difficulty on high damage. Your best difficulty setting is recommended. Once at Abyss, intentionally die on purpose multiple times. Continue, then die again. You will get 100 points every time a continue is used. When you finally choose to defeat Abyss, you will also get 50 points times the difficulty setting.
Enter the options screen. Select "Game Option" and set your difficulty bar high, choose the Turbo 2 speed, and have unlimited time. Put the damage bar on high. Go to arcade mode and choose any character with Cable (for example, War Machine, B.B. Hood, and Cable). When you begin at the first stage, make sure Cable's out first. Keep shooting with the pistol until your third opponent's life bar is half full. At this time your level gauge should be past 3. Use it at the correct moment and you will see more than 80 hit(s), plus the Perfect. You now have more than 300,000,000 points. Repeat this for the rest of the game .When you get to Abyss, be sure not to have him defeat one of your characters. Just keep shooting Cable's pistol until you get to his last form. On his final form, when Abyss shows up again, make sure your level gauge is at 3 or more to blast away.
Choose Juggernaut, Iron Man, and BB Hood (in that order). Put them all on their recommended assist types. Get 3 Hyper Combo bars and link them all together (L1=R1). It should kill the opponent in one hit. This move was tested on Cable, a medium damage taker.
Choose Juggernaut, Incredible Hulk, and Zangeif. When at level 3, let Juggernaut be your active character, get very close, and press L1 + R1 to make them all do their hyper combos. This will instantly kill your opponent's character. Note: This attack best works when your opponent is in a corner.