PSA: Please stop relating Adc directly to a mandatory bot lane marksmen.
Adc means Attack Damage Carry, not Marksmen Bot...
Attack Damage carry can be top, mid, or jungle, and does not have to be a marksmen. It does not even have to be ranged.
It means a Champion capable of bringing enough physical damage threat to give the enemy's a reason to build against it. The same applies for Apc.
Depending on the circumstances, a team doesn't actually "need" any physical or magical damage carry, so long as you have a way of killing the enemy nexus before they kill yours.
So please, stop embarrassing yourselves by flipping out(dodging or crying for someone else to dodge) when you see a mage go bot instead of a marksmen, and any similar scenario(tank mid, mage jg, etc..)