I beat every boss first try with 1-2 pokemon max. Even the infamous deathwing was a joke. I solo'd his entire team with just 1 pokemon and like 2-3 hyper potions. Just get some tanky pokemon that can power up with skills like dragon dance, calm mind, curse, ect.

 

I think it'd be nice if we couldnt use consumable items in the future (potions, revives, ect). Pretty much the strategy to 1v6 every boss is to use a tanky pokemon and keep powering up until almost dead and then use a hyper potion and keep doing that until max powered up.

well well.. I think 99% of the Bosses are way too easy, just for example you can solo Jessie and Pumpkin with a Gyarados... so how can that be hard^^