Dandy Ace

The main thing is just to take your time and slowly work down his health, do not rush and try spam attacks. Try and get your attacks to all have long lasting effects, such as bleed or burn, so that even when dodging and evading you are still whittling his health down. Look out for Axolangelo's attack when he fire's up into the sky. The projectiles will rain down and track your position, leaving areas that damage you if stepped in. When I saw this attack starting I would run around the perimeter of the arena, this way it would leave me a safe area in the middle.