Giovanni is just straight up mob boss, no backstory, no sympathy, just a man in it for money.

Rocket execs fucking sucked, their teams are all shit and they all just talk about a villain that you never fight. Feels like there should be more.

Maxie and Archie are probably third worst. Their goals are both incredibly stupid. ORAS gave them more character and made gr8 fanart, but that's it.

Cyrus is awesome. He's all enigmatic and shit but them BAM he's Pokehitler. Scary stuff.

Ghetsis is the best by virtue of being super fucked up. His treament of N is scary, the whole "Plasma pretends to be heroic" front is pretty neat, as is the fact Team Plasma had a weird religion to it with the sages and the crowning ceromony, really gives an "A God Am I" feeling. He gets even more badass in B2W2 with the black cape and hunch. He also straight up tried to kill B2W2 protag with Kyureem, no pokemon battles, nothing. No other villain has done that.

Lysandre a shit. "Oh if only I could purge the impurities of this world!" and we're supposed to act surprised he turns out to be evil. He looks pretty forgettable too. Just generally an "Eh, whatever." character. Points for dying, though.

Best thing Lusamine did was squeeze Lillie out of her vagina. I feel like she's Ghetsis, but with less badass and more 40 year old waifu. I like that she goes coocoo for UB-01 puffs, but honestly I think she should have died. A more itneresting story fo sho. The worst moment was when she turns into a black tentacle monster and... challenges you to a Pokemon battle. Really took me out of the moment. Like, shouldn't I be fighting that thing itself?

Guzma is a fun character but honestly a pretty shitty villain. Team Skull had fun an atmosphere but not even the game took them seriously.