Mirror Match refers to a match in which two players face off against each other using the same fighter or tag team. The word "mirror match" is often referred to as mirror battle or mirror fight.
Mirror matches can be done for fun or happen by chance. These matches also provide the opportunity for players to discover who has the better handle on a given character, and further understand their own play style compared to that of others.
During mirror matches, the game uses different models or textures for each players to distinguish them from each other. This way, players recognize which character on screen they control. While most other fighting games like Street Fighter and Mortal Kombat use different palette swaps for each player during mirror matches, Tekken initially used completely different outfits, although in some cases the alternative outfit is indeed a palette swap (e.g. Armor King and Anna Williams). From Tekken to Tekken 6, selecting the same character resulted in different outfits. In Tekken Tag Tournament 2, Tekken 7, and Tekken 8, selecting the same character results in different palette swaps. While Tekken 7 will not allow two characters to wear the same Default Outfit, it is possible for two characters in a mirror match to be wearing the same Preset Outfit. There will be no change in outfit if one or both characters are using a custom outfit slot.
Some characters however cannot be fought in a mirror match due to sharing a character slot and acting as a palette swap. Examples are Devil (Tekken and Tekken 2), Angel (Tekken 2 and Tekken Tag Tournament), Roger and Alex (Tekken 2 and Tekken Tag Tournament), Anna Williams (Tekken 3 arcade, due to being a palette swap of her sister Nina), Kuma II and Panda (Tekken 3), Tiger Jackson (Tekken 3 and Tekken Tag Tournament), Tetsujin (Tekken Tag Tournament - when unlocking Tetsujin golden version in versus mode, both players can choose Tetsujin until the player who wins ten battles in a row loses), Miharu Hirano (Tekken 4), and Eddy Gordo (Tekken 4 and Tekken 5 - although Eddy has two costumes in Tekken 5, only player 1 can play as him).