I'm about to battle with my friend and I know for sure that he's going to use protean Greninja. My Druddigon is adamant sheer force with 252 on hp, 252 on attack and 4 on special defense. Should I keep life orb on it or give it focus sash in case that my friend uses ice beam with that Greninja?
Life orb boosts your moves' power by 30%, but lets you lose 10% of your HP each turn. Focus Sash lets you live with 1 HP if hit with a move that could potentially OHKO. Of these two items, I'd pick the Focus Sash, because living with 1 HP is better than losing 10% of it each turn.
I'm gonna say focus sash to survive an ice beam. Then, protean makes it an ice type, and fire punch or iron head should be able to OHKO with greninja's low defenses+boost from sheer force.