They've made a number of balancing changes since this thread was posted. A very useful one is that you get three freebie max item upgrades so that it is technically no longer 'pay to win'. Zeraora has been debuffed and is now one of the worse pokemon in the game, although it's probably better in solo-q (ranked and solo-q are very different, Gengar is apparently great in solo but basically never appears in highest ranked).
But by far the biggest issue is, imo, the frikkin' terrible team mates and the fact the game can still penalize you if you get team mates AWOL; the bots that follow you are worse than the ones in the non-online mode as they steal all your EXP and just follow you brainlessly instead of being autonomous, and other MOBAs will not derank you if you lose a match with missing team mates.
The second issue is they don't bother to play-test their own mons before they release them, so a quarter of the time they come out extremely unbalanced and then get nerfed in a few days, which is quite stupid.
I have two different accounts just so I don't have to pay and get more freebie mons. One of them has a much higher win rate (56%-60% depending on the mon I play) than the other (which is barely above 50% because I keep playing Blissey and Pikachu which are very supportive and, well, Blissey can't do muk if your team doesn't show up for Drednaw/Rotom/Zapdos), which does illustrate that picking the 'right' pokemon for your playstyle (And which isn't too weak) is extremely important, but also when you choose to play. Playing at night helps avoid playing with literal toddlers. Getting friends is also good.
I hate to say, Zapdos is actually a balancing mechanism. Suppose you are getting beaten the entire damn game. What's the point in playing the last 2 minutes if there is no way to score enough to make up for it? However, the latest patch made Zapdos worse, because it used to be possible to use score shield if you lost Zapdos and defended hard to quickly score back, and now that's muuuuch harder; you pretty much have to wipe the entire team in the zapdos arena if they got it by luck and then have your whole team still be alive, which is possible if you prioritized Drednaw.
Most players don't realize prioritizing Rotom too much is a trap. Drednaw is actually the better option until later game, because not only do you actually want to lose your very first top goal so you get audinos for more exp to grind, but if you acquire it quickly enough then you should be able to jump back up top and wait on your goal to defend it from Rotom. Dumb, underleveled players who only go for Rotom will try to attack your whole team on the goal (stay close to the goal for heals, but be wary of pokemon that can push you off or straying too far and letting Rotom in, or of push attacks that can actively push Rotom /into/ the goal.) and die trying. Later game, prioritize last Rotom because it's like a free Zapdos.
Now that score shield has been nerfed, in solo-q sometimes the only time squishies like Pikachu get to score is with rotom and zapdos (because one attack will interrupt their scoring and probably kill them at the same time). So I have no problem with them per say, but a nerf to them could be very welcome.
For now, I've pretty much stopped playing the game. Lately my win rate has just been getting worse with the latest balance patches so there's not much point, and I already reached Masters once so doing it again feels repetitive.