The Power Instinct series is renowned for its more humorous take on fighting games, its music and its often-weird characters.
One of the innovations unique to the series was the introduction of the transformation feature. Several of the characters can change their appearance and fighting style by simply executing certain moves (usually a throwing move), though this hasn't been featured in every entry in the series. Other features include the ability to perform a double jump and attacking while dashing.
While the series has never been on the same level of success as The King of Fighters or Street Fighter outside of Japan, it has achieved a cult popularity in recent times. (Wikipedia)