Could i report people for unfair matchmaking?

That's a bit weird, since matchmaking is Riot's gig, not the players' gig. Could you please clarify what you mean?

no, riot's match making system , riot's rules : )

What is unfair matchmaking and how would a player be responsible for it? I'm very confused.

Unfair. I HONESLTY COMPLETELY UNDERSTAND YOUR PAIN. I do and I wish the same that one person who does belong in such skill level ruins it for thier team but as you riot never loved skill.

We the players don't have anything to do in deciding who gets in the match on either side. The one who has responsibility for matchmaking is Riot Games itself and we do not have a way to report them. On the other hand; We 'can' report anyone for anything, but that doesn't make those reports 'valid'.