Anyone in Team Rocket, for starters. They're a criminal organization that's a pretty huge nuisance, and their members have gone out of their way to harm people just for kicks. Strike fear into everyone's hearts, that sort of thing.

[Plus, they've got Cobra Commander on their side, and he's just ridiculous.

And as for the ice cream, Riku snickers...]

And yes, they exist. Just look up Vanillite and see for yourself.