My friend said that you have to either use a masterball or put it to sleep..

When you are going through the Aqua hideout there is a room. When you walk into it there are 4 items. Two are electrode and the other two are a nugget and the master ball. The left is the items and the right are the electrodes. I can't really explain how to get to the room but you will know when you find it. If you haave already finished this part of the game though you can't go bak in the hideout. The only other way to find a master ball is to win one in the lottery at lilycove.

When you are going through the Aqua hideout there is a room. When you walk into it there are 4 items. Two are electrode and the other two are a nugget and the master ball. The left is the items and the right are the electrodes. I can't really explain how to get to the room but you will know when you find it. If you haave already finished this part of the game though you can't go bak in the hideout. The only other way to find a master ball is to win one in the lottery at lilycove.

No that is not true,you don't need a master ball,or you don't have to put it to sleep,you could use any kind of pokeball.

Well, the masterball part is right but the other part is half right. You put it to sleep and weaken it, but not faint it. You find a masterball in the aqua hideout.

No it's not necessary at all, putting it to sleep or paralyzing it do greatly improve you chances of making the catch but it is by no means necessary. Same thing with a masterball, tons of people catch rayquaza with an ultraball or even a regular old pokeball. A masterball will 100% of the time catch the Pokemon you throw it at, but there is only ever 1 per game. Its located in aquas hideout I believe, the one with all the teleporters. For a Pokemon like latias or latios using a masterball makes the process about a million times easier, but for the ones that have a fixed position, just save before you battle and go nuts until you make the catch, reseting and restarting if necessary.

You don't have to use a Masterball, no. It helps to put it asleep,but it is not required.

The Masterball is in Team Aqua's base near LilyCove City.

You don't have to use your master ball for a rare Pokemon, just give it a status problem and use ultra balls, and you get the master ball deep in the team aqua hideout in the boss's room.

Actually I must say, this is probably the first time I ever heard a friend say something true. So yes this is true, it actually makes the Pokemon easier to catch [and it's guaranteed to be caught with the master ball]. Okay so I don't know if you've gotten to the point in the game where you're at the Team Aqua Hideout, to the far east of Lilycove. But if you've already gotten to that point, go in the hideout. I assume you would remember a maze of teleporters? Well once you've manuevered the teleporters, the room that it leads you to has 2 Pokemon [level 30 electrode] and 2 items [nugget and, of course, master ball]. The master ball is in the top left corner, so you have to either battle one of the electrode [if I were you, I'd attempt to catch one of them] or just collect the nugget on the bottom left. Or you can beat/catch one or both electrode, and collect the nugget and masterball...Whatever you want. That's just where the master ball is.

Try to lower thier special defence trust me it works I used it to catch Mew and Deoxy's.