Okay, there are 3 Methods I use when evaluating a Champion.
I use Win Rate, I use KDA and I use Average Gold. CS is important, but there are absolutely cases where you can get more Gold with Less CS. I don't advocate those, because CS is the easiest means... but you do what you can to get the Gold for Item Advantage.
Then I layer on things like CS (to see how much Gold you get is 'consistent Gold' and Average Damage Dealt.
This gives me a general view of your Impact on a Game with each of your Champions.
You have 5 Champions with a 3 KDA or Higher. Of those 5, only 2 (Wukong, Malzahar) have enough games to matter. Therefore, you need more games with Trundle, Darius and Ekko in Season 6.
Wukong and Malzahar have Win Rates at 67% and 68%, which is well above the 'Climb Threshold' of 55%.
You could, if you ONLY played Wukong and Malzahar, already be climbing. Just as I could if I only played Braum and Old Shen (over 62.5% Win Rate and over 4 KDA on both of them). But we need more than 2 Champions to consistently improve and have a greater range to climb with.
So let's look at your 2.9 KDA types, those that are very close to that 3 KDA.
Warwick is at 2.98 KDA, with a 78% Win Rate. You get 10.3 Kills with 8.2 Assists while only costing your Team 6.2 Deaths. You deal 48,941 Damage with Warwick as well, far above anyone else you play that has enough games to matter... with the exception of Yorick who we will get to later. You also sit at almost 16K Gold on Warwick, which is rather good.
Miss Fortune at 70% and a 2.90 KDA, adding only 21,922 Damages though. This tells me you likely position very well, wait for a group to get low, then blast that awesome Ult in to Finish... then give chase to survivors who already have depleted Health, so not much more Damages to put out to get those K/As. This isn't a negative thing, mind you. You might try getting a tad more damage in before the Ult so the Fights don't last as long and your Team takes less damage, but don't sacrifice your Positioning to do it. In other words... you're Good at MF, so try to push her to get a tad more out of her. No one can argue with the Win Rate, and the KDA is almost there... but adding more Damage will have a ripple effect over all facets of the game, by pushing people out of Lane more often (leading to greater Gold and XP Gains) to ending Team Fights faster so others don't die, to being able to Rotate to other Objectives because your Enemy are to low to follow to deny.
Jarvan... your only real issue here is dying a bit much. Even just dropping your D from 7.5 to 6.5 will do wonders for that Champion. He's already at 85% Win Rate, and a KDA of 2.85. His 33.5K Average Damage Dealt is a nice chunk of Impact.
Talon. I'd hold off on him for now. You have enough Roles and Champions, and you simply die a bit to much on him to be a major impact. You still manage to Win 61% of the time, so if Bans/Comp force you he's a nice 'extra', but you die 9 Times a Game with him. That's time other Champs would be alive and making a difference. Brush up on his Survival and he'll be great for you.
Yorick is the one Champ with a 'Low KDA' at 2.22 that I'd say keep playing, all the time. You Win 60% of the Time, while dealing 266K in Average Damages over 10 Games. That's... well... insane. I see you sustain a crap ton of Damage on you as well, but only die 6.8 Times a Game (despite the 368K Average Damage Taken). The only thing I can say is find a way to either CS more (like the 190 Kog gets, so only need to raise about 25 more CS per game) or finish off more Kills with him so you get the Gold to Power Spike faster. You output insane damages, and don't die a lot in comparison to the Damage you take... that your KDA looks very out of whack, it SHOULD be much better considering your ability to Tank/Sustain and Damage. The problem here is, outside of finding more ways to get Gold quickly for the Item Power... I'm not sure how to fix that.
Now you already know the Champions you aren't good at (like Teemo) or the ones that Win despite you not having much of an Impact (Gangplank)... but the amazing news is you already have a Pool just on this page large enough and capable enough to rise with, so the fix is to simply stop playing those Champs in Ranked until you improve.
You are at the point where your Ability on enough Champs is good enough to rise... so the next step is for you to start being a Leader. Shot Call. Keep people from losing morale. Build people up, don't tear them down. Keep them focused on Objectives, getting to and destroying the Nexus.
In other words, it's time for you personally to step up and lead... to not let every bad swing turn into a loss. Because even if you can only save 1 out of every 5 'lost causes'... that's 1 Extra Win that you need, so it's more than worth it. The ONLY way to Win those is better team play versus Teams that fail to close a game out (and down here, that's most teams).
Keep your foot down, if you ever get it on an enemy team's Throat, don't let it off. Always be chipping away... and while you doing that yourself will improve your play, the ability to get your TEAM to do that as well magnifies it.
Simply put, outside of Talon that needs a little work, you have the Pool to do this. You just have to enhance it by finding ways to make your Team Mates better. It's time.
Best of luck in your climb.