The phrase "playable fighter" refers to a character in a video game that can be controlled by the player. They can be used to fight against other characters or complete challenges within the game. Full definition
Speaking of characters, I was initially concerned that the launch roster of playable fighters worked too similarly. (eurogamer.net)
They are dedicated to their character appearing as the new playable fighter, however personally I am not a fan and thing this is not a really satisfying idea. (gameluster.com)
They were most recently seen as playable fighters in PlayStation All - Stars: Battle Royale battling against other PlayStation icons such as Kratos and Nathan Drake, and exclusively on the PlayStation 3 version of Street Fighter x Tekken. (bitcultures.com)