Theres a difference between borderline trolling and going "off meta" where you draw that line is different for everyone for what's acceptable and what's not but if you're going to pick an ADC to support another ADC you're going to have a bad time (with Ashe and MF being very situational picks to counter specific situations). They have the exact same weaknesses, and you'll be the more useless one of the two because at least the one you're "supporting" is getting some gold from cs.
Honestly please don't do this in solo que. If you wanna try this in flex que as a 5 man thats fine but don't do this in any other iteration of ranked. There's a reason there is a set number of champions that go where they go, and where they are viable. You are handicapping your team by picking stuff like this cause these champs are not equipped to reliably fulfill their role needed for the team outside of very specific skill sets. I'll explain why below,
Graves is a carry. That means hes gold reliant. He's one of those champs that are okay if fed, garbage if behind. He requires you to get close to deal damage, but will get blown up if focused. So he relies on being able to blow up his target, but he can't do that if he doesn't get items which require a lot of gold. Your friend recommending Graves as a tanky - engager? He doesn't have an engage?? If he uses his only dash to go in he'll get nuked immediately unless he has DD and PD (two items you'll never reach in lane phase unless the enemy team is inting). Outside of being a wardbot, Grave's really can't do much as a support. He can't peel, engage, doesn't provide any form of sustain, you're basically gonna be a large minion in lane for the enemy to farm. Not to mention tilting your team off the face of the earth. You're making the game a 5 v 4 by being useless at best, and a 6 v 4 if you end up feeding the enemy bot lane without providing utility for your own team to make up for it.
Jinx is also a carry, which read above is gold reliant too, something you will never be able to play at her full potential on par with everyone else in the game, unless you're stealing CS, or getting enough kills to make up the gold differential. At the very least, Jinx has some utility but even so its not reliable, and really telegraphed. She also suffers from being useless without gold, see above with Graves.
As funny as this might sound, Nasus and Nunu are what you can consider "off meta". They aren't traditionally picked as support but they have the tools to make for a decent one if played well.
Nasus has arguably the best slow in the game, point and click, with a cripple (Attack speed reduction) being applied to an ADC is devastating for their damage output. His E has relatively high base damage, and armor shred making you and your ADC hit a lot harder. He can zone, and engage and not have to worry because hes a tank and can front line for your ADC. I feel like the only reason he isn't picked as a support is because he cannot stack (unless you take relic shield) , is weak to double poke and doesn't have a hard engage.
Nunu, has a telegraphed engage that is easier to dodge than most support engages (think Leona, Ali, Thresh, Blitz etc.) but has an attack speed steroid, multiple slows and stuns and a fair amount of sustain with his Q, and he exerts a fair bit of jg pressure later into the game.
Point being these last two picks can "support" as they can fulfill the original role to a reasonable degree with their kits. They will require more work to be good but they have the right tools. ADC's generally don't.
Edited for spelling and grammar.
or 
to help them in trades. Those that cannot trade in lane without being chunked (Pyke/Thresh), they take 
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Graves.