If I made a list, the merican yo-kai from Yo-kai Watch will be there. Yo-kai's monsters in general are unappealing, but the mericans are just so stupid and lazy that they make the older monsters in the series look good.
It didn't look too bad until the redesign but the same thing happened with Steven Universe. I imagine that it's much harder to get an animation budget these days when Adventure Time and Regular Show reveal just how low the bar can be for cartoons now, even when they want to attract an older audience as well.If we're gonna mention Bravest Warriors, please include Bee and Puppycat for looking even poorer than Steven Universe. It's only right to do so.