Why Is MissingNo. a pollywhirl

I blame a▓▌▄▓░▒█▀▌▀▄█▲◦â—█▓■▪■â–██▌. a▓▌▄▓░▒█▀▌▀▄█▲◦â—█▓■▪■â–██▌ has the encounter and capture flags of a Pollywhirl, and I think MissingNo. can steal sprites on occasion.