Am I the only one who can't stand facing riven right now?
For starters, her fucking shield is way too massive, especially in combination with a blood thirster. If I had a dollar for every time I've seen her narrowly escape engagements she shouldn't be able to lately I would be able to buy all of her skins. And it's an escape/chase AND it's cooldown is 6 at max level AND she's manaless.
Insane. I hate it!
And since everything she has including her shield scales massively off of her bonus AD, all she has to do is build massive damage items. She can delete people like Kha'zix could last season.
Her ultimate is like an instant win button.
The last 3 games I've played with her on the enemy team, she snowballed epically bad and destroyed everything.
Watching her constantly escape/delete my team makes me want to FREAK out.
I play (and play against) Riven quite some times and these are my two cents about her
First thing is, get a ranged champion. Or a champion that can either freeze lane with no problem or can farm under tower (basically a Rengar :P)
Now, first thing that counters a Riven is how you plan to play your early: she's one of the strongest early game champions and usually a lane with a good Riven ends with her having scored some kills at the end of the laning phase, thus making her a snowball-machine
For this reason, the first thing you want to do is to starve her both of cs, both of kills: even if she doesn't show it, she has problem farming at early levels, since she relies quite a lot on her passive to get proper last hits; thus, she needs to use her skills to proc her enhanced auto attacks; however, by doing so, she pushes lane, since they are all AoE (except E, but no sane Riven relies on it for farming); by pushing lane, she does 3 things
-She gets less farm, since early farming with her Q-W is not that good
-She puts herself on the risk of getting ganked
-She cannot try to engage you, since you're near your tower
Now, if you pick someone, as I said before, that can either freeze the lane, either farm with no problems under tower, she's bound to be completely useless until extreme late game (where everyone has full builds), since damage items cost more gold than defensive ones (but building defensive items on Riven is as good as building her full AP)
This is one side of the coin
The other is about getting someone with good range harass
Not many people know this, but Riven has one of the lowest HP Reg in the game (she's something like the third of fourth). If you think you're good enough to bait her shield or to either deal a lot of damage on her even with her shield, consider this option, since it will force her to either take a Teleport on champion select (thus reducing her killing potential if she were to take ignite), either to lose gold and experience by recalling
About teamfights, just remember this: she has to get in front and personal to deal damage. This said, you can either poke her down, either burst her and retreat (retreating in this case is easier, since she's the one who gets closer to you guys). Just don't get all near when she starts with her combo or you're pretty much fucked
About champions who can counter her, here are what I've read about
-Garen and Cho'Gath are considered some good counters because of their silence and their executions. However, by my personal experience, I'd be careful about choosing them
-Kennen is considered a good counter because he can easily harass her and escape from her engages. Also, if she tries to all-in you, your R and passive should just destroy her
-Another one they say counters Riven is Renekton, because he can engage as hard as her but, instead of her, he can out-sustain her with his Q
-A good one with which I had lots of fun once is Mordekaiser: because of his kit, you put her in difficulty for early farming (since you can easily push her to her tower) and she can't possibly engane on you without suffering more than you do
-There are also Olaf and Darius, but I didn't read (nor now I want to imagine) how they counter her
I hope this helped