Lusamine is the toughest opponent of the story before the League: a team of five Pokémon with no shared weakness, which you face twice, the second time with an aura that powers them all up. Here is the method, Pokémon by Pokémon.
Aim for level 42 for the Aether Paradise battle, and level 50 for the Ultra Space one. The battles against Foundation employees and Faba just before give enough experience to close the gap if you left the Exp. Share on.
The principle is simple: her team mixes Fairy, Normal and Fighting, Ghost, Grass and Water. No single type dominates it. You therefore need a varied team, and above all a plan for Bewear, which can sweep a poorly prepared team all by itself.
