Bishop: 70's costume
Colossus: Xtreme costume 2
Cyclops: Xtreme costume 2
Jean Grey: Dark Phoenix costume
Juggernaut: Original costume
Magneto: Ultimate Non-Helmet costume (starting costume without helmet)
Nightcrawler: Xtreme costume 2
Rogue: Coat costume
Scarlet Witch: 70's costume
Storm: 70's costume
Sunfire: 70's costume
Toad: Brown costume
Wolverine: Ultimate costume

Successfully complete Act 1 to unlock the following costumes:

Colossus: 70's costume
Cyclops: Original costume, 70's costume
Iceman: Snowman costume
Jean Grey: Phoenix costume, 70's costume
Nightcrawler: 70's costume
Storm: 70's costume (another one)
Wolverine: Original costume (Brown and Gold)

Successfully complete Act 2 to unlock the "Age of Apocalypse" costume for all characters that have them.

Successfully complete Act 4 to unlock the following costumes:

Colossus: Xtreme costume, Gladiator costume, Ultimate Non-Steel Skin costume (starting costume with normal skin)
Cyclops: Xtreme costume, Snowfields costume
Iceman: Non-Ice Skin (the same as in X-Men Legends)
Juggernaut: Original Non-Helmet costume
Nightcrawler: Xtreme costume
Storm: Xtreme costume, Snofields costume
Wolverine: Weapon X Experiment costume, Xtreme costume, Snowfields costume

The bonus characters already have the following costumes available:

Deadpool: Unmasked costume
Iron Man: 2099's costume, Age of Apocalypse costume
Professor X: Shadow World costume (the same from X-Men Legends)

Team bonuses - Use a team with the indicated characters to get the indicated bonus:

Age of Apocalypse (Any four heroes with Age of Apocalypse costume): +100% attack rating
Agile Warriors (Nightcrawler, Sunfire, Toad, Deadpool): +5% experience points

Brotherhood of Evil (Juggernaut, Magneto, Scarlet Witch, Toad): +5% experience points
Bruiser Brigade (Juggernaut, Colossus, Wolverine, Rogue): 20 energy gained per knockout

Dark Past (Rogue, Deadpool, Gambnit, Wolverine): 5% damage inflicted goes to health
Double Date (Rogue, Gambit, Jean Grey Cyclops): 20 health gained per knockout

Energy Corps (Gambit, Bishop, Cyclops, Iron Man): +5% damage

Family Affair (Magneto, Professor X, Scarlet Witch, Juggernaut): +5 health regeneration
Femme Fatale (Storm, Scarlet Witch, Rogue, Jean Grey): 5% damage inflicted goes to health
Forces of Nature (Storm, Iceman, Sunfire, Magneto): +10 to all resistances

Heavy Metal (Colossus, Juggernaut, Iron Man, Magneto): +10 to all stats

New Avengers (Iron Man, Scarlet Witch, Wolverine, Bishop): +15% maximum health
New X-Men (Nightclawler, Storm, Colossus, Wolverine, Sunfire, Bishop): +15% maximim health

Old School (Cyclops, Jean Grey, Iceman, Magneto, Toad, Professor X): +15% max energy

Raven Knights (Iceman, Professor X, Iron Man, Deadpool): +60% techbit drops

Special Ops (Bishop, Deadpool, Nightcrawler, Gambit): +5% damage

Easy experience - For easy levelling up, go to the Holding Pen level. There is a location where enemies keep teleporting onto the screen; it is just before the last area entrance. Note: If you stay too long without saving, your game will freeze.

Easy items - In Act 2 after you rescue Beast on Mikhail's Warship, Blink will open a portal back to Avalon. Go through the portal to Avalon then immediately return to the warship. The scene of rescuing Beast will play again, and the ship will be undamaged. You can go back and get all the items again. Repeat this as many times as desired. Additionally, to get easy Techbits, health packs, energy packs, and items, return to the top of Apocalypse's tower where you fight Archangel. Smash all of the containers to get random free items. Repeat this as many times as desired.

Have Gambit and Toad on your team. Have Gambit use Prince of Thieves, and Toad use Plunder (this requires at least two extreme points). Do this when near a weapons cache and you can get about five times the amount of what you would normally get. This includes health/energy packs, and Techbits, but you still only get one special item.

Good combo - This combo works when you have Wolverine and Juggernaut on your team. With Juggernaut, walk over to Wolverine and pick him up, just as you would do to a chair or other item. When you throw Wolverine, he will do a diving attack to nearby enemies. This also works if you need to send Wolverine over large holes.

Strong Gambit - Once your characters get to about level 30, use Sunfire, Bishop, Toad, and Gambit as your team. The idea is to pump up Gambit as much as possible. Put as much of the stats as possible into each ability as follows: Sunfire = Flaming Fury, Bishop = Energy Fury, Toad = Secretion, Gambit = Energy Form. Also, put an extra 6 or 7 stats into each characters Mutant Mastery so that they will recover EP faster. During the game, activate all the abilities listed above and switch to Gambit. He will be able to run very fast and be super strong. Eventually he will have +200% movement, +400% or more attack and many of damage and defense bonuses. Also, because they regain their EP fast, you can reuse the abilities as soon as the affects wear off.

Strong Iceman - Iceman is the strongest character in the game. If you boost him correctly, he can kill most of his opponents with just a single hit on melee attack. Distribute his Status Points wisely, developing more on his Focus and Speed. At his Projectiles Mutant Powers, concentrate on his Cold Crush, and a little in Freeze Beam and Ice Slide. Do not spend Skills Points in Boost Mutant Powers, as they are useless. Also, if the rest of this is done correctly, Iceman will grow strong enough to easily fight alone. Spend the maximum you can in his Passive Skills, particularly in Ice Combat and Cold Mastery. Get the Danger Room Disk: Challenge - Iceman, and get and equip his Signature Unique Item, Cryogenic Booster. That brings a very good trait, Double Cold Damage. As for other equipment, put some that give bonus to Damage (not Energy Damage, Electric Damage, or Radiation Damage). If done correctly, Iceman can hit easily his enemies (because of the high Speed), hit lots of enemies with the Cold Crush Projectile Mutant Power, and will inflict lots of damage. For example, you can do 500 and even more damage with melee attack, depending on your level, because of the Passive Skills, Ice Combat, Cold Mastery, and the Cryogenic Booster Signature Unique Item.

Recommended team - Having two blasters (for example, Magneto) and two brawlers (for example, Wolverine) works well. The following team is highly useful, because there are times where you will need a mutant with super strength to move an object out of the way. If you need a bridge formed, use Magneto. If you need a flyer, both Magneto and Ironman will work. The heavy metal group is Colossus, Juggernaut, Ironman, and Magneto.

Final area - First, step into the power chamber in the middle of the vault of ages. Since there is only a limited amount of time you have to use the harmonic powers, choose a faster character to do this. There is a yellow meter that will show you how much harmonic power time you have remaining. Go straight up or straight down to reach the generators. The downward path has a small maze in it. Go right instead of left. At the generator, Apocalypse will be waiting. You must beat him up before you can destroy the generator. Destroy the generator and repeat the same process with the other one. It does not have a maze, and it will be a straight shot directly to it. Just like before, Apocalypse will be waiting for you at the generator. After destroying the power of the harmonic machine, he will bring statues of the horsemen to life. You must focus your attacks on the horsemen and get them out of the way before tackling Apocalypse. When you kill the horsemen, they will return to statue form. Then, kill Apocalypse twice to complete the game. Note: Make sure you have a full load of health and energy packs before attempting this.