ADC and support. Bot lane period.
Firstly, they both have to have good positioning.
Tank supports need to be the front line or else yelled at. They need to engage in a good way, peel for their ADC, CC, and be a meat soaking body blocker for skill shots. Especially Braum.
Buff supports(Soraka, Sona, Nami, etc.) generally have to stay at the back line, keeping their squishies alive and peeling for them, as well as not dying themselves.
The ADC has to, as you said, position correctly, and they're the main ones for carrying through the lanes and taking towers. They also have to keep lane frozen or pushed so they can help their jungler get drag when he needs it, as well as pull lane when their jungler is waiting to gank.
And overall, the main thing that pisses me off whenever I play ADC or support, is the cooperation between the two. If they lose lane, both blame the other. If they win, all goes well, they continue going good, and carry the game. And its a lot easier for them to lose their wits than not, because y'know... League community. Make one mistake and its "WTF DUDE STOP THROWING!" "WTF NO PEEL?!" "DUDE ENGAGE WHEN I DO!" "STOP FEEDING!" and as most everyone knows, its mainly the ADC, and the support gets yelled at if he doesn't ward every single bush and possible gank path on the map.