the problem with grand bosses is that  1. Time Restriction, Culprit Eidolons. 2. Weapon damage difference is too high. - Snipers out perform almost all rifles. The only way to fix is to have Snipers do reduced damage but only do a full amount of damage when they hit a sonar like spot on the boss that appears from time to time. - But also give weapons like Rifles, Bows, Melee ways to attack using attacks like hand to hand combat or utilizing warframe energy.    - For Example, take DMC5's