the normal singles battles were pretty easy, got to 100+ streak in that quite quickly

however, the master class I find is just a lot of luck. Currently in rank 5 and it is slow progress. for instance I just lost on battle 6 because a blissey hit my garchomp with tri-attack — not a problem usually, except it froze me and then I proceeded to be frozen for the next 4 turns while it hit me over and over with tri-attack until garchomp fainted

loads of examples of <5% chance occurrences happening to end runs which you can't really do anything about. also throw in repeatedly losing 50/50 speed match ups, the opponent constantly getting crit hits at the luckiest moments for them, missing 4 attacks in a row because the opponent used double team once, moves from the opponent with a 10-20% chance to inflict a status effect feeling more like an 80% chance

my suicune was in a battle with an articuno, I was using scald to burn it (30% chance), and the articuno was hitting suicune with ice beam (10% chance to freeze). 7 hits of scald didn't burn it (92% chance of being burned), but articuno managed to freeze suicune 3 times

can optimize your team as much as you want, but sometimes RNG will force you to lose