Give Poppy Sustain
Poppy is not the only Toplaner without sustain, but the other champs have reliable shields and cc. Poppy's shield relies on her wither finishing a minion, or walking to it, which in a lot of match up can be close to impossible. And her cc relies on the enemy to walk close to a wall and unlike Vayne, she has no dash to get in position. And even if the enemy is against a wall, a simple dash can completly deny the stun.
Giving her sustain would help her to atleast keep up, otherwise she can easily be buillied out of lane
or
had sustain on top of their HP/Armor/MR scaling. Or if
or
also scaled with Armor or MR their heals scale off HP, but that's the only defensive scaling they have in their kits.