Ok so I just wanted so start a discussion on the common misconception surrounding grinding in MMOs. Particularly the phrase "PRO is an MMO and grinding for hours/days is a part of all MMOs". Now lets just get one thing out of the way, yes this statement is mostly true, and I am not here to dispute that MMOs typically have grind-fests at some point. The main difference between PRO and the good MMOs is where and why you start grinding. In good MMOs the true grinding starts right before and during the endgame. In PRO the grinding becomes very heavy before the kanto elite four. Which for both the pvp and the pve people is not the end-game in fact personally I would consider it the mid-game, this is because after the kanto elite four there is not only two other regions but also several bosses with level 120s to get through, pvp still has to get to level 100 and max evs to do. The other major difference is the reason you grind. In the good MMOs you grind for better gear to do harder dungeons/bosses to get better gear,this is very similar to the minor grinding between gyms imo. In PRO you grind to cross the level gap between the last 1-2 gyms and the elite four but after the elite four instead of finding better training spots/pokemon you still have several quests and bosses to do/fight before you get to those places.(love island, cerulean cave, etc) You do get to go to johto but then you have to regrind and there's even more bosses/quests in johto to do which require grinding. Now I'm no game designer but I've played countless MMOs and spent countless hours in a few that have a lot of grinding, but I'm fairly new to PRO though I have played a lot of pokemon (not so much competitive) so I understand how to setup teams and movesets, so feel free to correct me if I'm wrong.
probably the easiest way to remedy this is increase wild pokemon levels/xp in victory road or add a separate grinding spot for the elite four to make the grinding more in-line with the curve for the other 8 gyms.(you could even make the pokemon uncatchable so as to keep the catchable pokemon lower leveled)
Tldr: the phrase "PRO is an MMO and grinding for hours/days is a part of all MMOs" is an incomplete statement because the grinding is in the wrong spot and for the wrong reasons.