There are hacks out there that give people more energy in PvP, give people 3 shields, and allow them to take less damage. Some examples from first battle of match:
My Graveler vs. foe’s Rapidash (Little Cup). Sims show that I should easily get off a third rock blast to KO Rapidash before foe gets off a third Drill Run. In this battle, he fired off Drill run #3 just after my second rock blast. No lag on my end, just crazy fast energy generation on his.
Foe leads Obstagoon into my Fortress. My bug quick attack should be chomping him something fierce. Sims show that I win in all but the 2-0 shield matchup. In game, he not only beats my Forretress using no shields, he also takes out my Mantine before going down, and he didn’t get any night slash buffs that displayed. Maybe he came into the battle twice buffed already, … WTF?
Reported both matched to Niantic, suspect nothing happened since I didn’t video it. Frustrating to grind for PvP pokemon and practice using them only to lose badly to cheaters.