I've never used any of my masterballs, I'm such a pro. (?)
Haha no, I'm just lucky I guess...
Pokémon White FC: 0476 3940 2635
Pokémon Diamond FC: 2452 0987 4240
I caught Lugia in a Pokeball and the Tao Trio in Ultraballs.
I've caught every single legendary in a non-Master Ball, except maybe Mewtwo. It's not like it's impossible.
I've caught every Legendary at some point or another (the ones that you can catch) without the use of a Master Ball. I had used it on some in earlier playthroughs of games, on stuff like roamers, or things I couldn't be bothered to catch, (like Rayquaza) but at some point I decided Ultra/Dusk balls work, and the Master Ball is better saved for a shiny.
On a first playthrough of any game before Gen IV, I believe I would use the Master Ball on whatever the version mascot was, or Mewtwo if it was a Gen1 game.
Entei (quick ball), Raikou, Suicune, Azelf, Uxie, Giratina, Dialga, Palkia, Zapdos (ultra ball in blue making it much harder since the ball misses most of the time), zekrom, thundurus, kyurem, virizion, cobalion, terrakion (timer ball), landorus, reshiram (poke ball). I use ultra balls for anything without the specified ball next to it.