1. dont rely on lowered difficulty. ig: if 1 person cleared it in 1 day since that NE was released, the difficulty will be lowered by one, and the next condition is 4ppl cleared in 3 days. but if that condition isnt met, the difficulty will never lowered anymore.

2. try other ninjas, either have high dmg, or field dmg, or interruption/chaos/immobile (chaos and immobile may likely be control failed) (in this case, knock tsunade first, she heals twice, annoying...)

3. worth a shot to try premium ninjas (if u got any), reccommend hokage minato (yeah i know he's expensive and not rly that good in pvp, but he's super strong in pve, well his standard in pvp is outstanding)

4. doing NE is about strategy. so find somewhen u have lots of free time (2 or 3 hrs) and with a good mood, try to *ize and counter the problems (usually by changing mains, passives and carriers (main dmg output ninja)).

PS: i used hokage minato for 259 too (hehe) at 120k bp, difficulty lowered 1/7 , so if you dont got him i wont be any help to you, but feel free to do experiments and share your lineup (dont have to be f2p, but not that op like 6path naruto xD)