It really depends. If you aren't going to use your master ball on anything else, then using it on Groudon is fine if you want to. But you can catch it with a Poke ball or Great Ball, etc.
Use dusk balls or ultra balls. It is not worth it to use masterball because groudon is not so hard. I caught groudon with only 3 ultra balls.
Which pokeball should you use to catch victini. Well i used the normal pokeball but in my opinion i think that you should use the ultra pokeball
Depending on where you are in the game it's alright to use a normal pokeball but a great ball is what I used to catch it you should not waste a masterball on victini it's not hard to catch just lower it's hp down before you catch it.***EDIT*** Different person writing.For me to catch Viciti I had to try many attempts to catch it, I used a NEST BAll, which worked. Different people have different luck, some used a pokeball, greatball, ultraball, but i used a NEST BALL and it WORKED.
the strongest pokeball is the masterball. the masterball can catch any Pokemon out of the 493. it doesnt matter what kind of Pokemon it is, the masterball can catch any Pokemon.
Perferably your Heavy Balls or your Ultra Balls. Possibly even Level Balls or Dusk Balls.
Ash used a lure ball.
any kind, i used a pokeball
you catch it in a pokeball, you see a pokeball is a ball that can be used to catch certen Pokemon and they are ranked from how well they work. the most popular ones are pokeball, greatball and ultra ball and even a masterball these are all used to catch your Pokemon where ever you are. have fun catching them sincerly from I anomonys. so keep trying and never give up even at the hardest of times sssssssssssssooooooooooooo have fun mate and hopefully you'll catch a pikachu, I mean phanpy.
you just need to get the master ball off the galactic grunt boss it has a 100% catch rate hope i helped or you can buy lots of ultra then go to terra cave (thats where find and weaken groudon down real low like about its about to faint but dont kill it then try to catch groudon with an ultra ball this will take patience.........lots of patience
use it any Pokemon that u have trouble catching u don't need it to catch mesprit or cresslina i used pokeball
Ultra balls are to be used for any legendary that does not roam PERIOD.
If you haven't used your master ball yet you should try using a repeat ball better quality then a net ball. Net ball, it's got 3X catch rate for water and bug types.
Of course, the best pokeball to catch any pokemon is a master ball, but if you used it on dialga, you could put it asleep and then get its hp red and use an ultra ball