Where can I get a Master Ball in Pokemon Sun & Moon? I'd like a reference just in case since I find trying to catch legendaries without them very painful -- up to how many Master Balls can I find/get and where can I do so?
In theory, you can get unlimited Master Balls from the lottery. Getting a match of all 6 numbers on the lottery will rewarded you with a Master Ball.– SGRNov 21, 2016 at 10:08
You recieve a single Master Ball as part of the main storyline.
There are two ways to get additional Master Balls, with no limit to the number you can recieve in total.
Playing the lottery at Hau'oli Tourist Center will give a Master Ball if you match 5 numbers.
Playing the Big Dreams Lottery in the Festival Plaza will award a Master Ball as the top prize. Higher stars increases the chances of getting this prize.
You get one free Masterball free during your playthrough of the storyline. However, you can get more (and potentially unlimited) through the lottery at Hau'oli city - if 5 out of 5 of the numbers match, you will get a Masterball as a prize.
A way I found to easily get a master ball is to find Pokemon with the pickup ability and run around until you find one.
5This doesn't work, sorry. Jan 3, 2017 at 21:30
6The Bulbapedia page for Pickup lists all items which can be received through the ability. Master Balls are not and never have been available. The only types of Pokéballs that have ever been available through Pickup are Great Balls and Ultra Balls. Jan 3, 2017 at 22:18