Phase 6, requires 7 star everything for platoon missions. Only the guilds with the oldest deepest rosters will get a chance at getting lvl 3 power ups.
Phase 5&6 is also tuned for G12. So no easy mode to 3 stars in those phases. Your current maxed gear 11s wont survive more than 4 waves in combat missions without serious rng, stuns, tm control, daze and resists.
Those platoon missions bonuses will be critical to get you to eek out a win in phase 5&6 so getting those done first will be the goal.
Happy catching them all.