Demyx has a lot of potential to be a very challenging boss. He wasn't given enough credit or anything, but he did have lots of combo's and he was really quick.
He just wasn't used to his full potential in the game, and even though he was ticked, I think he was still holding back. Granted, Demyx is more of a Defensive boss, rather than a Physical one. Don't get me wrong though, since he used lots of attacks that involved him coming in contact with Sora. The water clones, his wall of water geysers, and the bubbles he'd shoot at you from a distance also goes more into the fact of being a defender rather an attacker.
He just wasn't used to his full potential in the game, and even though he was ticked, I think he was still holding back. Granted, Demyx is more of a Defensive boss, rather than a Physical one. Don't get me wrong though, since he used lots of attacks that involved him coming in contact with Sora. The water clones, his wall of water geysers, and the bubbles he'd shoot at you from a distance also goes more into the fact of being a defender rather an attacker.