If you don't like changing your team over and over again don't even bother continuing. It's important to have a dynamic team or otherwise you just won't be able to cope with the upcoming challenges. I have like a set of 20 pokemon that I use on rotation. It makes it fun because you get to play with pokemon that you otherwise would never play with such as slugma, meowstic, pachirisu, ... Try to have an open mind and change some pokes around.
Yeah, reborn is a tough game. And without the right strategy, it'll take a lot of grinding and re-dos. But in the end, I think it's all worth it.