How do you deal with grinding? I'm about to go fight the elite 4 but this team can't really manage them, though I got to the fourth guy by doing some serious save summing and checking which pokemon is weak to what.

I think average level of around 55 would be enough to beat them without much of a hassle but leveling that much would take ages and this stage always seriously demotivates me. I can happily do a small amount of grinding in the beginning of the game where it actually makes a massive difference and isn't such a chore, yet at higher levels it's tedious as hell. Why is there such a massive difference between late gyms and the elite 4? This is not fun.