Finished survival/ultimate training at 37-38k, 35k for power training, and speed training was a complete joke. It seemed pretty under-tuned compared to the power they recommended in most of the challenges, although that might have been because I used water main and cheesed through a lot of the difficult fights by abusing neurotoxin and/or poison.
Hardest fights for me were the later Raikage trials where everyone is immune to debuffs, particularly the ones with cursed Hidan + other high damage characters.