In Persona 4 Arena Ultimax, there are several hidden versions of characters in addition to their normal and Shadow forms. These are called Boss Modes and are only unlockable after completing a series of difficult challenges.
To unlock Boss Mode, sometimes called Unlimited Mode, for a character in Persona 4 Arena Ultimax you need to complete the Arcade Mode for that character on the hardest difficulty, Risky. Completing Arcade Mode on Risky difficulty will display the message “Boss Mode for X has been unlocked.”
Related: How to report bugs and errors to the developers of Persona 4 Arena Ultimax
You’ll now be able to select Boss Mode for these characters in Arcade Mode. To do this press the Y, Triangle, or whatever your Persona Light Attack button is bound to, on the Character Select screen during Color Select.
Boss Mode characters are effectively highly powered up versions of the characters, similar to a fully leveled character from Score Attack. They often have unique abilities or specials, such as expanded meter, higher damage, or other effects.
For example, Unlimited Yu has flawless attack cancelling and an increased chance to inflict status effects from his Zio attacks. Or, Unlimited Chie who has Power Charge always active. Unlimited or Boss Mode characters can’t be used in online or other modes, but can be used in Arcade or Versus against your friends just for fun.
For more Persona 4 Arena Ultimax guides check out How to solve the inviting friends issue in Persona 4 Arena Ultimax on Pro Game Guides.
Michael lives in the UK, but wishes he lived in Eorzea. A life-long gamer, Four years ago, he ditched a "real" job to write about video games for a living, and hasn't looked back. When not guiding players how to get the latest mounts, crafting recipes, and in-game goodies, he spends his time nurturing an unhealthy addiction to MMOs and gacha games.