Because I was using my Geodude and a Zubat used Supersonic on me. After only one turn Geodude snapped out of it. This happend twice and I got the same result both times.
But when my Chimchar was confused it took him 3 or 4 turns to snap out of it.
Oh, no. There's nothing like that in the games. All Pokemon (regardless of type) will suffer Confusion for 1-5 turns. It's generated on a fully random basis.