League of Legends (LoL) Question: which champion i use to beat yasuo

Are you talking about midlane yasuo or toplane? Basically you want to be able to damage or cc him without having to land skillshots because yasuo counters just about any and every skillshot reliant champion (ahri, xerath, varus etc). Ranged autos are also nice since you can remove his passive shield without wasting mana and cooldowns. If I'm tryharding I pretty much always pick annie against him...its yasuos's nightmare lane

I think Malzahar counters him pretty hard. That said, you CAN'T easily beat a good Yasuo player. It's too complex of a champion to have a "simple" counter, so a decent/good Yasuo player will wreck you if you're not decent/good yourself.

i find jax works well once you get sheen and ninja tabi

I like using Veigar, his stun keeps him from getting on you and you can easily burst him down. I do however agree with Ekki that a good Yasuo player is very difficult to beat.

Maybe Kayle, for her E (Area Damage) and resistance.

Akali reks him after lvl 6. Just need to avoid his knockup (last breath) and not get ganked before 6 by junglers.
(You dash him and then Q Mark of the Assassin +AA to proc so he can't windwall. Dashing with good timing can get you behind him when he is doing his Q Steel Tempest and thus he won't get stacks or do you any DMG)