If you are referring to the Magus Sisters in Final Fantasy X, then...
1. Weapon with the "Capture" ability.
2. Flower Sceptre
3. Blossom Crown
1. Go to the Calm Lands and go to the west side of the map, and enter a small area which will lead you to the Monster Arena. Talk to the man there and agree to help him capture Fiends. Buy a weapon of your choosing from him with the "Capture" ability.
2. Head to Mt. Gagazet and defeat every enemy there. You must land the final blow on the enemy with the weapon that has the "Capture" ability, or you wont catch the monster!
3. Head back to the Monster Arena and talk to the man again. He will give you the "Blossom Crown" as a reward for capturing all the monsters on Mt. Gagazet.
4. Stay in the Calm Lands, get on a Chocobo, and head towards Macalania. There is a path that can only be taken by Chocobo near there. This will take you to Remiem Temple.
5. Fight Belgemine's Aeons, and defeat her Bahamut to obtain the "Flower Sceptre."
6. Head to the Chamber of the Fayth in Remiem Temple. Enter to fight and obtain the Magus Sisters.