I'm lvl 76.. I can get top 3 if I use coupons for 30% buff.. and I can get top 3 too if the others don't use coupons.. I mean "Big $ players".

I'm full f2p, and I manage to bought at 20% iruka in this event.
My ninjas used are Fire 4* / Iruka 2* / Anko 3* / Guy 4*... Everyone gold +2 except anko he is only gold +1 awakened and fully cultivated.

Well Currently I'm using mood + atk - defense... since I was playing with wind main, I still need more meat* to change it, because I used a lot in my tobi / hinata.
The crit sometimes reach 23k using Dragon Flame. I'm using tonton "summon" he can reach around 17k - 18k critical with 30% coupon buff. Can't remember if using coupon buff the Dragon flame reach around 27k with critical. Need to check but not today.. I'm still farming some coupons for the curent event.

Iruka without buff his chase critical can do around 12k.. with 30% coupon buff he can do around 14k to 15k.