I’ve been trying out Gloobin lately. Since his main move (Bubble Bomber) will stale out your style meter whether grounded or in the air(unlike Champ, who’s aerial and grounded tail jab count as separate moves) and his other attack move (Spicy Burp) has a high cooldown, you need to utilize Artesian Waters and his other attacks Snack Conversion and Spicy Burp in order to keep his style as high as possible.
For me, I start off with some Style potions (Artesian Water or Exotic Artesian Water). Make sure to pay attention to your Spicy Burp and Snack Conversion cooldowns, and use them ASAP to keep your style up while fighting.
With this strategy, it is pretty easy to beat Normal difficulty bosses in under 5 minutes, and even under 3 minutes if you are fast enough. Just make sure you stock up on some Artesian Water in case!
Also, in the Victory Cafe, I STRONGLY suggest Deluxe Lemonade (Damage Invincibility lasts 4x longer). Gloobin has very short range, meaning he will get hit a lot thus losing style. With Deluxe Lemonade, you will get hit much less and your style will stay much higher.
edit: I was just able to solo Queltod on Extreme in UNDER 5 minutes with Gloobin! Make sure to utilize the invincibility on Bubble Bomber (refer to PRIZZA’s post) and the Deluxe Lemonade. Collecting as many element extracts as possible for Snack Conversion.