Mick
Spongebob because he's annoying and always the centre of attention.

Keith
Patrick because let's face it, they're both stoners. Also because he's "Spongebob's" best friend and accomplice.

Brian
Gary because he's smol and everyone loves Gary!

Charlie
Squidward because he's sick and tired of "Spongebob" and "Patrick's" shit and has been putting up with it for years.

Bill
Plankton because WattsupWatts said so... Lol I'm kidding. Because he's little and "spongebob" annoys him.