Hi, gold main supp here. I play a lot of normal games too so i've came across a lot of troll damage dealing supports. And the way to deal with them is always the same: just be patient and don't go on tilt. Sometimes, you gonna meet trolls supports that are so good at making your laning a living hell, that you wonder why they're not becoming legit. And its simply because laning is just a tiny (yet decisive) part of a game, and does not entirely decide the output of the game. The first 3 level agaisnt troll supports are generaly hard, and you have to watchout for theyr lvl6 ulti powerspike.

As a support, your priority is to not give them any kill. Even if thats mean not engaging this one time you feel like you could get a kill. If its not a 100% secured kill and your river isn't warded: don't go.

As an adc, you just need to be willing to lose one or two waves with an early recall. Be patient, try to get as much CS as you can and you'll be good.

The logic behind that, is that you don't need to actualy DO anything to outscale a Brand support. You can just wait for him to be starved for gold. Because, if he don't get any kills, he will not be able to buy the mana regen and AP he need to be helpfull to his team. And will end up just being a dead weight. He might even steal CS from other laners, or go for a juicy minion waves on a lane instead of grouping to help his team, making the game easyer for you.

However, if he manage to get a kill, he could become a second AP carry for his team, and then they gonna try to end fast, before he begin to fall off.

So lets say you want to play Leona, and you face a Brand support. Just keep in mind that laning is not the whole game, and if laning ends with no kills for you, and no kills for him, (and your adc have a decent CS) you actualy won the game. So its easy for you, because you don't have the pressure of getting a kill for your ADC. Use your stun and exhaust to stop theyr engage and ganks, and suck it up while he spams his abilities. You just need to get trough the 8 first level. Get the turret. Get the drake. And you just won.

Of course if you really want to help your ADC, you can pick a sustain support who can help your getting trough this laning phase without losing much CS. But its not mandatory. It will just help you making the laning phase easier.