You're wrong about a few things, and that just tells me your opinion is skewered. No wonder you get bodied by Fizz mid, you don't even understand several things about him. So let me point out where your wrong, and explain why you need to actually git gud, and that it isn't Fizz being too strong =) Bear with me, open up your mind.
Fizz's Flip renders him Untargetable, Invulnerable, allows him to close distance, and does damage with no drawbacks.
Two things wrong with this so far: Fizz is NOT invulnerable during Play/Trickster. Things like Ignite, Malzahar Maelefic Visions, Teemo and Cass's dot poison, Karma's W tether Lb's tether, will still damage Fizz while he's UNTARGETABLE. The fact that you believe this is evidence how very little you know about Fizz. And we all know how people complaining about things they don't understand go. You blame your loss on Fizz being "over powered" yet you don't even understand how Fizz works. Surely your lack of knowledge on Fizz contributed to your loss?
The second thing wrong, is that his E has no drawbacks, when in fact it has more than one. First off, simply using it means that he won't be able to use it again for (at best, maxed rank and cd) 12 seconds. Just like Blitz's Q, a Fizz without his E is much different than a Fizz with his E up. A Blitz that just missed his Q is a joke until it's back up. A Blitz with his Q up is terrifying and a threat. By sheer virtue of using his E Fizz puts himself at risk.
(Small note: Yes Fizz can use his E as a gap closer. But no, he doesn't. That's what his Q is for. He has two possible gap closers, but only 1 Escape. Good Fizz players gap close with Q, and escape with E. Since using Q to escape requires a targetable enemy unit behind you to dash through)
It also costs (gasp) mana. A looot of mana. And other champs have cooldowns and mana costs, and for those champs they matter too. You don't seem to realize how incredibly taxing a 90 mana cost spell at RANK ONE is. Fizz pays a massive chunk of resources in mana to use every single E. So onto your next point.
Each of these status's/effects are powerful enough to be considered ults on some characters. Kayle, Twitch, Rengar, Khazix, Ekko, Rek'sai, Kai'sa, Xayah, Nocturne, Etc. have two maybe 3 of these effects as their ULTIMATES, Ekko being the only one with all 4.
Now, I already pointed out that Fizz is NOT Invulnerable during E, so we can go ahead and take out Kayle. To be honest I'm even sure why you put Twitch here, since his stealth (Untargetability) is on his Q, he isn't Invulnerable, not sure a range increase helps to "close distance" and "does damage with no drawbacks" isn't true since Twitch can atually MISS with his bolts fired during his Ult since they don't track and go in straight lines.
Right, that leaves Ults that make the user Untargetable, gap close, and "does dmg wtih no drawbacks"(Which I'll say out right is wrong, since in order to dmg the enemy with Fizz E you have to be in melee range, and thus you are in range to be retaliated upon. There are drawbacks wether you notice them or not)
Rengar: Makes him Untargetable for a substantial period of time. Rengar can move during this period, reposition, cover great distances, and gets bonuses and buffs to his next attack, and an automatic passive leap. This isn't even everything his ult does, since using it can make the entire enemy team back off and play differently. But this all seems fair for an ult. Fizz's time window of Untargetability is nothing compared to the length of Rengar's ult. Rengar's gap close is vastly superior to Fizz's range on E. Rengar's ult has no drawback, since he can use it and not even have to go in to affect the enemy team, thus no drawback, no risk. Fizz's E has risk. So really, this is a poor example for you to use.
Khazix: Can go Untargetable two, up to THREE times. Entering stealth, procing his passive and Duskblade, as well as Sudden Impact Rune. Fizz goes Untargetable once. Khazix can be even harder to get to than Fizz. Khazix can go Untargetable 2-3 things, plus he has a JUMP, that gets extra range when evolved, and RESETS on kills/takedowns, making him HARDER to hit and get to. Another bad example, Khazix is actually harder to pin down than Fizz. You're not arguing your own points well so far.
Ekko: Ekko doesn't become Untargetable, or Invulnerable during his ult. It's a blink, and a heal, and his sheild is probably involved, and it nukes for massive damage. I have no idea how you even compare Fizz E to Ekko's R, let alone how you want me to believe this supports your argument either. What?
Rek'sai: Goes Untargetable just like Fizz E, for longer period of time. The gap close is also far greater than Fizz's E. Plus Rek'sai can gap close with Burrowed E as well. So Rek'sai's R out performs Fizz's E. And it's her Ult. Seems fair. What's your point?
Kai'sa: Her ult grants her a sheild and a massive gap closer. However, it neither makes her Untargetable nor Invulnerable. She gains Stealth on evolved E, but at no point does Kai'sa beecome Invulnerable. Again, you demonstrate your lack of knowledge of the game, and are talking about things you don't understand. Frankly, you're making wrong points. This is me pointing out the fact you are wrong, and explaining why you are wrong.
Xayah: The only parts you're comparing here is the Invulnerability. So I'll bring up the area of effect and cone is far superior and deadlier than Fizz's E. Xayah using R has even less drawback then Fizz using his E. I'll also use this chance to mention Fizz's E mana costs are on part with Ultimates. Sooo.....why are we saying Fizz E is overpowered. Because Xayah R?
Nocturne: He does not become Untargetable. Impairing the enemies vision with Darkness does not remove their ability to target him within range. Nocturne is Invulnerable to Spells when is spellsheild is up but that's not his ult. It is, however, a gnarly gap closer! It's ten times the Gap Closer that Fizz's E is. Bad choice to compare, since Nocturne's R basically curb stomps every aspect of Fizz's E. Not making your points that well. Not selling them to me.
So all those champs, that have Ultimates and mechanics put into their power budget, and Fizz gets watered down similarities to an Ultimate move on a basic ability, with the same Mana as an Ultimate ability, long cooldowns, and similar power budget to basic abilities? Right.....seems like that's how things were intended to be.
You brought up all those champs and I point out how each of those champs Ult's also brings either more or better of what Fizz's E does, or entirely new and unique things that Fizz's E can't do. Let's move on, and address more of your grievances with Fizz.
Fizz having all that as an ability with a 12 second CD is waaaaaaaaaaaay too overpowered no mater how you look at it. The ability has no drawbacks to use that aren't just basic problems every character has (Like CD or Mana consumption) and does far too much considering the rest of his kits damage.
If Fizz is maxing his E, to do all this magical "tons of damage" you're talking about, than his Q and his W wil not be hitting as hard. If Fizz is maxing Q, his E's aren't hitting this hard. If you want to argue at higher lvls when he can max his E and his Q, that's a point where everyone is doing the same, maxing more than 1 ability, reaching near to full builds, ect, and as you say yourself becomes a moot point. If he uses it, wether the trade went his way or not, he still pays the mana cost (very high) and gets the cooldown.
Plus, if he wants the slow, or the larger AoE, he has to wait on his Pole and drop naturally to get it. If Fizz activates Tricker, he hops off the pole, his AoE is much smaller, and he doesn't apply the slow. The risk and drawback is the skill expression in landing Playful, which is harder, as opposed to landing Trickster, which is easier but less rewarding. Walk out of his E AoE and stop standing in it. The "rest of his kit's damage" only comes with Items and Skill Points. Only his E has a good Base dmg value.
Everyone here has seen a fizz throw his ult and flip simultaneously and destroy your HP in 0.0 seconds. I have an actual screenshot of him doing 2.3K in 0.0 on a match i wasn't behind on.
No one has seen that. That is hyperbole. That's akin to saying "Ashe Ult is op because it does two billion dmg" It's wrong, it's silly, it's exageratted, and no one is going to take you seriously or put any weight or validity to your arguments. This doesn't serve your debate at all, so don't do stuff like this.
The reason i mention his Untargetable status with his ult because it renders him invincible from tower damage as well.
So does Vlad's W pool. Akali's Shroud did the same thing, actually it used to be worse! Yasuo's R puts him out side of Turret range. Pantheon's PASSIVE can block a Turret shot, and it resets on each W and every 3-4 auto's/Q's. Oh, might as well say any champ with Untargetability can do the same thing, because they can. Zhonya's can be bought by anyway. Stopwatch is even cheaper. What is your point?
Its problem is the Invaun status when he uses it, The fact hes completely invincible in the two seconds hes moving makes it too OP.
It's essential to his Kit. It's his escape. An assassin without an Escape either needsd durability to poke and all in, or the raw damage to burst down their target before they blow up. If Fizz didn't have Untargetability on his E, Riot would compensate his loss of abiilty to get out of a Fight or drop the back line but frontloading more dmg onto him. So he can succeed at taking out his target, and then he dies.
I still have more to say, I want to type up closing thoughts on how and why Fizz is managable and isn't problematic. And if anything, the issue with him isn't on his E at all. All of Fizz's moves are skill shots and can be dodged except for his W. You can dash or flash or use any kind of hop or such to actually avoid his Q, and it should be clear that it's possible to dodge the AoE of his E or the linear skill shot of his R.
But before I type up anymore I want to give you a window to read what I've said so far, and to respond.