Fizz's troll pole can be adjusted

Low the mana cost, remove the untergatable thing, instead give him damage reduction with a low base amount that scales up with ap, this means that in early game he is really weak and in mid-late game he will be strong with a bunch of items. And if you wanna keep the slippery identity you can give him tenacity/immunity to snares while Eing. So you can stun him, but he he is still super hard to catch.