Mata Hari, Drake, and Caesar would likely be allowed. Iskander Cursed Arm, Asterios, the onis, and Lu Bu aren't. Asterios's maze is a pain in the ass to manage. Cursed Arm Instant kills. Ozy is too strong. Iskander is Grand Rider, and his phantasm is too strong if he wasn't. The onis both have skills that allow them to do ridiculous things in lore. 

Astolfo is fair game relatively I may reconsider due to his shield, and flight being issues. I'd need to read up on Bradamante in the wiki if I am to consider her though from what I've seen she's probably a no.