Are there any champs that you just don't get?

Champs that when you play them it feels like you're trying to read a different language or something? When you try to combo with them you just fuck up and end up misclicking and pushing every button. When I first starting play that champ for me was Pantheon. After I started getting better that champ changed to Rengar but after some time I got pretty good with him and was able to not feed my ass off with him every game. The champ that I have never been able to wrap my head around is Udyr. Every time I play him I just suck so bad. I even had my friend who is a big Udyr player help me out and I still just couldn't do it.