6. Cuphead - Wally Warbles
For the most part, the bosses in Cuphead are no joke. While they might look like they're straight out of a children's cartoon, they will crush you like an episode of Black Mirror. And as this shady bunch isn't ever going to go down without a fight, they will try everything and anything they can to get the edge over you and your mate Mugman, including adopting multiple forms.
However, while Goopy LeGrande won't even let death itself stop him from "having a go", Wally Warbles ends up in much worse condition during his boss fight. After you've smashed apart his house and killed his...er child (don't think too much about it) you then have to take on Wally who is being assisted by two medical themed birds (air ambulance?).
It's a far cry from the feathered foe who tried to cover the screen with blue razored tipped death as now Wally either spits out literal garbage for you to avoid or DIES as his heart leaves his body for a short while. Just give it up mate, this is just embarrassing.