He can be a pubstomper but it's pretty risky to pick him unless you know who you're facing in draft. I think he can really snowball off of popular champions like Vlad, Orianna, and Karthus though. And ganks should pretty much never stop you once ahead
Oh, no, never, ever pick Fizz against Vlad. This would be the worst decision ever.
I argue why :
-Fizz HATES being zoned/harassed. What can you do at level 1 if a Vlad is between the creeps and you threatening you with his Q? Then later? Fizz is all about burst, he got no sustain, Vladimir Q is instant so he can't avoid it.
-The only thing Fizz can do is wait, let's say level 3, then go. And what happens? Vladimir Q and pool and that's it. He starts harassing again.
-Level 6, Fizz should be stronger no? Well, no. If Fizz ultimates Vladimir just has to pool. Even if the "shark" was on him, it will do no damage under the pool. So yes, you can't kill him and he can harass you forever. Since he got sustain and you don't, you'll be forced to go back and not him. Of course you can avoid his ultimate if you time well your E but that's all. Vladimir will win the "farm game" and you will end up having no kill on your lane, which is terribad when you play Fizz.
-If you gank, Vladimir pushing ability will doom your turret and make you fall behind.
Fizz is strong against Twisted Fate, because he got nothing to avoid your spells (bar flash of course) and can't stun you if you time your E well. And trololol you can send a shark with him TPing with ultimate (or interupt it).
It's far from being a won lane against Orianna and Karthus given their range and their ability to push the lane. If your enemy can kill your wave in two spells, trust me you'll have issues playing against him. Especially when you know that Orianna is not easy to kill at all.
I'd say that Fizz also crushs Anivia, since it's easy to avoid her stun, and that you insta burst her with 2 spells given her paperness.
Fizz is a funny hero, but it's an assassin, good teams will shut you down. But yup, it's a skilled hero that can be deadly in some situation and that snowballs mid really hard. However in the team fights you will be weak as hell, you can finish low hp people or take the paper heroes on 1v1, that's all.