These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
That One Boss: Telepin goes without saying. Also Carlton. Deskel could also count for some. What makes Carlton all the more frustrating besides the fact that he appears so early on is that he's a self-admitted miniboss. ("I'm not really interested in being a boss...")
Carlton is an interesting case. He's usually called challenging due to him being a Flunky Boss, but if you kill enough of the Mooks then you can level up midfight and restore all health.
Medium, mostly the second form.
Viewer Gender Confusion: Tablet's voice and appearance are rather feminine. It can take until Pastel calls him the Devil's son for his gender to be cleared up for some. Telepin's gender is also hard to figure out.