Alternate Skins List

Alternate Character Skins are available through various Downloadable Content packs and merchandising offers.

Batman: Arkham City
Alternate Batsuits were available as pre-order bonuses for Batman: Arkham City. Following the game's release, a "Skins Pack" became available on the Xbox Live Market & the Playstation Network, enabling Xbox 360 and Playstation 3 players to obtain all of the pre-order batsuits.

Batman: Arkham Origins
Alternate Batsuits are available as pre-order bonuses for Batman: Arkham Origins. Some can be unlocked in-game, or through other methods. Alternate outfits for extra characters are included on their DLC packs.

Batman: Arkham Knight
Costumes/Batmobiles are changed by hovering over them in the showcase and pressing "Select skin" button. Unlike the previous games, all costumes can be used before beating the game, without using cheat codes, with the exception of DLC Batmobiles that are not based on the default Batmobile.

While inspecting a character model, pressing "attack" turns on Black and White filter (Characters) or Battle Mode (Batmobiles). Pressing "counter" turns on slow motion.

Certain Batmobile and Costume descriptions reference other Batman continuities. Explanations for these references can be found here.

Other Characters/Notes
Joker, Azrael and Batgirl don't have any alternate skins. Until purchased, DLC skins do not appear anywhere in the games.

In Arkham City, Origins and Knight (After the September patch), a special big head mode can be activated by holding the furthest shoulder buttons and spinning the right analog stick clockwise for ~10 rounds on console, and on PC, it is activated by. In City and Origins, Story mode needs to be completed first, but this requirement was dropped in Knight.

In Arkham City, pressing Left, Left, Down, Down, Left, Left, Right, Up, Up, Down in the main menu allows using alternate costumes in default story mode before completing it, but the default Batsuit is still shown during cutscenes. This cheat needs to re-entered each time player returns to main menu. Note that this code only allows using already purchased alternate outfits. In Origins, using this code still plays the "code accepted" sound effect, but doesn't actually do anything. This is most likely caused by reused coding.

Differences in Batmobiles
See the Batmobile/Guide article

Trivia

 * Oddly, The Arkham Origins skin that can be downloaded for Batman: Arkham Knight is based on the Dark Knight skin that can be unlocked in Batman: Arkham Origins and is not the default Batsuit Batman wears in that same game, though it is called the 'Arkham Origins Skin'. It is either an oversight or developers simply preferred this version.
 * Though in-continuity it could be that, at some point after Arkham Origins and Arkham Origins Blackgate, Bruce decided to make the Batsuit black to blend in more in the dark before switching over to the more familiar Batsuit seen in Asylum/City.
 * In Batman: Arkham City, the costumes based on Batman: The Animated Series have both cel-shading to resemble the characters from the cartoon, as well as noticeable outlines around character models when these costumes are in use.
 * Additionally, Animated Batman's outfit is the only one to affect other character's costumes when in use.
 * According to Rocksteady, the developers worked hard to get the sound of the 2016 BvS Batmobile "just right".
 * The 2008 Dark Knight skin was never meant to be made. This would have made the Tumbler the only Batmobile that lacked a Batman skin as a DLC skin to accompany it. It was thanks to considerable fan demand from the Arkham community that this costume came to be, which ultimately released in December 2015.
 * Before they started creating the skin, they asked whether the fans wanted the costume from Batman Begins or The Dark Knight. Needless to say, the Dark Knight skin won.
 * Similarily, the Arkham Knight outfit for Red Hood and Classic Harley Quinn outfits weren't planned to be released; in October, due to fan requests, Rocksteady asked users to vote either #TeamArkhamKnight or #TeamClassicHarley, and the winner would be made into a playable skin. However, due to an unexpected amount of votes for both sides, they both were eventually made.
 * In Batman: Arkham Origins and Batman: Arkham Knight, certain alternate skins have capes that don't extend all the way from arm-to-arm while gliding, instead resulting in Batman visibly holding his uncovered arms in the same position as normally while gliding. As weird/humorous/annoying this is, it's not a glitch, as the suit's capes were not designed for gliding in their original continuity. Without redesigns, the cape's width would not be wide enough to match the Gliding animation, leading to this effect.
 * This effect is the most notifiable in Red Son costume in Origins, Flashpoint costume in Knight, and First Appearance in both. In addition, Robin's classic TV series suit seems to suffer from this as well.
 * Curiously, before a patch had fixed any bugs/glitches present in the game, whenever players ejected themselves from the Batmobile while wearing the original Arkham Batsuit, for a brief moment the cape would lose its detail and show signs of damage. The most unusual part is that the damage shown is the exact same cape damage from Arkham Asylum, with the rips and tears being in the same places they were in the first game.
 * Curiously, the Earth-2 skin for Knight has randomly appeared on the Xbox marketplace, but installing it has no effect. Searching Earth-2 on the PS Store shows Arkham Knight among the top results, which also happened if one searched for the previous DLC shortly before their release. This could mean that it may still become available at a later date.
 * According to a forum moderator, the Earth-2 skin was planned to be released alongside the January DLC drop, but wasn't for unknown reasons.
 * The description for the Jokermobile is an obvious reference to the various Joker hallucinations in Arkham Knight during the City of Fear story mode.
 * In Origins, The Dark Knight Suit is the only alternate suit to have battle damage.
 * Deathstroke's playable version is often criticized due to his moveset being heavily similar to Robin's in Arkham City.

Gallery
For more, see the Gallery Page.