He is very weak early on, but he is just as unkillable as Nasus lategame or maybe even more. I once myself took on a full build master yi and a ap carry at the same time and won with more than half hp. They were both fed early game.

Try to sustain and farm, if and when you get harrased, begin the spawn of zombies and give some basic attacks back to use his passive correctly. Yoricks E heals him which is usefull if you get your hands on a lot of mana

If you think he goes all in ult on yourself and use the combo q, e, w. E at middle as it heals, so you want to lose some hp so you wont be wasting that effect.

Come in from the side to start the ingage, which he is good at, with his tankiness, speed and slow. Ult the AD carry early to win the fight.