I know only two ways.Beat the eighth gym, and professer Juniper will give you a master ball.If you also trade with 50 people over wi-fi connection, someone in the Castelia city Pokemon center will give you another master ball.
The only way to get more Master Balls in Pokémon X and Y is from the Lotto ID in Lumiose City.
Every day it will randomly generate a number and if any of your Pokémon have an ID that matches all five numbers, you will receive a Master Ball.
Alternatively, you can ask someone to trade you one.
No
well the max of master balls you can get is 999 but you can only get more master balls in trades.
Pokemon lotery and action replay
you need to buy a master ball or find one you cant make a master ball
you can get all of the poke balls you could in Pokemon ruby, Sapphire and emerald. that being poke balls great balls ultra balls net balls and only 1 master ball but not only though's you can get dusk balls luxury balls and also 1 master ball so yous it wisely and sorry if that's not all the poke balls witch I'm pretty sure its not but that's not all i would be able to tell you more but some 1 stole my Pokemon pearl so sorry again
No
action replay
You can't you only get more if you have the cheats
Have your friends trade you the master balls they got.
well the max of master balls you can get is 999 but you can only get more master balls in trades.
buy them at walmart
give one to a Pokemon and trade the Pokemon with the master ball.
You trade Pokemon from friends that's Pokemon is holding a master ball
more like 493 master balls. its a cheat on the AR look up the code for it. its called Pokemon modifier.
Pokemon lotery and action replay
use a game shark
Hacking