>>58512535>You should naturally get to that if you do maybe 30 runs of Infinite Z-A Royale.You're aware you can just do your reward matches in the middle of the night and continue, right? If you're picking up bonus cards, this only usually translates to about 12-15 trainers per reward match. This is even a more efficient way to get money (pic related, I hit the medal cap with just 42 battles).
By the time I had hit the 15 streak, I was only sitting at around 400 trainer battles.
There's basically nothing you can do to make the trainer grind faster since the limiting factor is how long trainer battles take, not how many you can fit into a night (time doesn't progress during battles, in menus or in cutscenes).
If you actually want to make it "painless", you're better off just camping Cafe Le Nah and doing it semi-afk or entirely afk if you have some way to automate it. Even then, it's 3 battles in about 2 minutes and 15 seconds.