Facing Ekko
I will start this post with a question first. I am Bronze 3 and I actually wonder what do people think about when they're banning champions? "Omg this is the most OP champ, ban him!" So far, that is the only thing I can think of when players ban champions. I may be Bronze 3 in Solo Queue (Bronze 2 in Twisted Treeline sadly), but even I know that ALL champions have a weak spot; Especially Ekko. 
I have seen Ekko play 3 roles so far (or at least by the time I posted this), which was Top, Mid and Jungle. When Ekko is level 1, he'd most likely start off with his Q, which is Timewinder (I think that's what it's called). It slows you each time you are hit from it and when it comes back to Ekko, that's when it deals more damage. At level 1, that move and his passive (slows an enemy and deals more damage after 3 basic attacks, speeding himself up as well if three strikes were dealt to a champion) are the only 2 things he can use. Usually you'd just want to dodge his Q and make sure to look at where he is at to dodge the follow up as well. If you are confident enough that you can deal a lot of damage to him after dodging his Q successfully, go for it.
Ekko becomes more of a problem the more he levels up (same with all champions), so while facing him... you'd have to study each and every move he does. For example: His AoE slow (dont know the name of it) that he enters giving him a shield and stunning everyone else that is still inside is very hard to avoid, you only see where he uses it after about 2 seconds. You can only "prepare" to dodge that move by listening to Ekko, cause normally you dont hear enemy champions say anything other than them using their /d, /t, /l, etc. If Ekko says anything, be very cautious about what you will do next because you will get stunned if you don't try to avoid his slow/stun. (Oh, and let's not forget about the passive of that move which basically obliterates anyone under 30% health)
His E is nothing more than an empowered basic attack that starts off as a dodge (or a roll if you want to be more precise) and ends teleporting to a short distance attacking an enemy champion. He might just dodge one of your skills though with it, or even use it to get closer to his AoE that he placed. You COULD wait 2-3 seconds to let his "empowered basic attack" cancel out and setting it on cooldown, or if you are gutsy enough...just attack, but I highly recommend the first idea.
When he learns his R (and is not on cooldown) you can see where Ekko was 4 seconds ago, but that's only if you have vision of him as well. When he uses his R, he will teleport to the spot he was at 4 seconds ago and dealing damage in an area around him, he will also heal most of his health that he lost within that time period. Even I think this is a really powerful skill and it sometimes makes me think Riot is crazy (sorry Riot) for making a skill like that. But what if you force Ekko to use it? If you can scare Ekko into using his ult WHILE you are away from his afterimage... (or before image, I dont know...his pixelated clone?) he wont be able to use it for probably 1 minute and 30 seconds on average (so that's not accurate timing) So really you wouldn't have anything to worry about afterwards. Or you can just keep Poking him so that when he does use it, he wont even heal very much of his health because he didn't have very much of it 4 seconds ago.
Since most of Ekko's skills trigger slowing effects (and speeds him up if he basic attacks a lot), I would be crazy enough to use a summoner spell such as Exhaust
but that is only an idea. It slows an enemy and also reduces their damage dealt, which is basically putting Ekko into your shoes. Or you could use champions that also have a way to dodge while using their skills (Graves is one of those champions
) Tenacity (which Irelia abuses a lot
) will decrease the time of the crowd control effects that are on you. In this case, stun and slow are the two Tenacity will help you get rid of. Of course if you aren't Irellia, you can only have 1 item with Tenacity (Irelia has just 1 item and her passive). Quicksilver Sash
and Cleanse
Completely removes all CC (Crowd Control) effects you have, although they have cooldowns as well.
There's a lot to think about when facing Ekko. To put it simply, going aggressive will PROBABLY backfire commonly.
Edit: Well his W got nerfed, you can see it 2 seconds after he casts it... let's see if this helps ya'll defeat him