I'm no expert, but what I think helps the most when playing Kog'maw or Varus (2 really fun ADCs) is how good your support is.
Kog'maw and Varus obviously have no mobility, but their huge lane bullies. It's really hard to out dps/poke them down. This is really too bad becuase you end up shoving your lane as either of these champs, which then opens the door for the jungler or mid to come down and clean you up, and you don't have great mobility to get out of it.
So how do we fix this? I'm not sure if it's something worth fixing, it's a lot easier to play champs that have less lane presence, but higher mobility like Graves/Cait/Sivir. But if you're truly inclined, the support is the big key here. I find Braum to be exactly what mobi-less champs need. He's got a long range slow, one of the best support passives, and a nice engage/disengage ult. But what really helps you out, is the fact he can block most projectiles for you. This gives you a lot of time to either get out safely or turn the fight due to your high dps. But there's a lot of good support champs that have great disengage.
In the end, I don't find lane phase to be all that difficult on Kog, Varus, or Ashe. As long as you're warded well, and pay attention to jungle/mid ganks, you can come out no less then even. Problem is when team fights start, playing with a mobi-less ADC requires greater peeling, which nobody in solo queue wants to do. I personally don't like playing Kog or Varus without a duo partner or a full team, because we can build teams around them. Ashe is a little different because she brings her own disengage.
Anyways, anything CAN be effective in solo queue. I would think going BotrK then Tri-Force would be the strongest start. I'd probably build BT last if not at all on Kog. BT is generally good on champs with good AD scaling abilities. You're already getting life steal from BotrK, and with W, you're a health % shredder. So I'd probably build IE first since your auto attacks are where most of your dmg comes from.
I'd play him in a couple normals, get a feel for what he's like vs champs like Jinx, Sivir, and Kalista. And possibly try to find a duo support main.
