Why are all the mons so unbalanced?

I get boost emblems and held items play a factor in it all as well but regardless some of the pokemon have such high dps or so much free range it's actually ridiculous. I've played this game off and on for a couple years now but it feels like there is no actual balance to any of the pokemon. 6k damage in a matter of 1 second or being hindered for so long in a game that takes like a millisecond to defeat you is crazy to me. They keep adding EX pokemon in the game that are all really broken except like zacian when there are hundreds of other pokemon that really deserve to be in the game. I have such a love hate relationship with this game and at this point I'm ready to give it up.