Mermalair Starfishman to the Rescue Guide

Atomic Flounder: Approach him immediately so he starts attacking right away. Study his attack patterns to know when he's vulnerable.
Sinister Slug: Run away from him while he's spinning. Start approaching him when you see he's about to stop spinning. Make sure not to punch him until the white ! symbol appears above his head.
Jumbo & Hermit: Punch them right at the start to skip having to wait for them to finish speaking. Wait for Jumbo to charge at you and punch him when he stops in front of you. From there, dodge Hermit's attacks while still staying relatively close for when Jumbo starts to charge again. Staying close to them slightly reduces the distance they need to travel during the charge attacks.
Prawn: Run circles around the edge of the arena to dodge his blow attack until he becomes vulnerable. Pretty self-explanatory.
Dirty Bubble: Hit all of his mini bubbles before he proceeds to his blow attack. From there, stand at different points in the arena depending on what phase you're on and start running clockwise or counterclockwise to dodge his blow attack. You can start approaching him to punch him the second the white ! symbol appears above his head.
Man-Ray: Run circles around the arena and jump to dodge his freeze ray attack. Stay about half a disco tile in front of him while still running in circles until he becomes vulnerable. Alternatively, you can start approaching him right before he becomes vulnerable and tank a hit to save a small amount of time. From there, you must wait for him to try to counterattack and block the attack and quickly punch him three times. The time window between punching him and his counterattack becomes smaller as you progress through his phases, with the last one happening almost immediately after you punch him.