Apart from the obvious, that ult that steals your stats and isolates you, his level 1 with a q start matches up on the strong side with most top laners, level 2 is a powerspike with arpen and grab and faster passive proc, level 3 gives him a shield.
A champ that scales so hard should not have such a strong early game.
I played poppy into morde and had a phage and null magic mantle. He had amp tome health crystal and boots. He turret dived me (he was 90% i was 75%) and i got turret stun with E, landed both hits of Q, ignited him, and used r for knockup, all under turret, and the guy escaped with about 10% hp after killing me (flashed away from turret)
His kit is fine his base stats need to all be reduced by like 15%