3rd Gen What Pokemon did you use the Master Ball on?

In my very first playthrough of Ruby (which was my first 3rd-gen game), I just used my Master Ball on Groudon. At that point I was still in a sort of 'aaah mascot Pokemon, Master Ball nao!' mindset. After that, though, I NEVER used the Master Ball on a Pokémon that wasn't a Roamer. So from there I'd use the Master Ball on Latios, whichever Legendary Beast would appear in LeafGreen, and then whichever Eon-mon I chose in Emerald.

In Emerald, I used it on Rayquaza :3 I didn't bother to keep pressing a and b and I didn't want to waste Pokeballs so I just used it right away. lol

Well, my first time was when I was little. I saw a wild Pelipper, thought 'Wow, a big sprite! It must be powerful!' Used the Master Ball, never used it.

Now I tend to use it on runners.

Lol, I remember that i catched a Linoone with a Master Ball on my Ruby.
I used a Master Ball on Rayquaza, Because rayquaza was my favorite Pokemon, so i didn't wanted to waste balls so that's why..

Oh yeah... Magikarp. My friends told me it was really good and I believed it, then when we battled I beat them cuz I had a Gyarados. However my first masterball was on a Ponyta in Yellow.

I just replayed all Gen 3, and every time I used the Master Ball on the roaming legendary.

All other legendaries took me 30 or so Ultra Balls to catch (each).

The only exception was Mewtwo in LeafGreen: one Ultra Ball without inflicting any status effects and after only one attack. I was lucky :) .

I actually was smart enough my first time to catch rayquaza with the masterball.

Like most of the others who have posted here, I used my Master Ball to capture Latios in Ruby version because one of my friends who had already finished the game told me that it would keep fleeing whenever you encounter it.

As I recall, it was with Rayquaza in Pokémon Emerald. Now I regret having used it, because it could be used UltraBalls without any problem.

I used my Master Ball on a shiny Hariyama in Emerald, I figured I could catch any legendary with an Ultra Ball.

I used my Master Ball on Latias in Sapphire and Latios in Emerald, I think (it's been a while). I don't think I've used mine yet on Ruby, nor have I used my Master Ball in LG. I'll probably use it on the roaming Pokemon in those games, as I can't think of any better purpose for it.

I don't remember the details of my other legendary captures, but I think I caught most of the generation 3 legends using several Ultra Balls apiece (anywhere from 2-30ish?).

The first master ball I used was on Rayquaza.

Age: ~9-10.

1. Fire Red: Zapdos (Age 7-8)
2. Emerald: Latios (Age 9-10)
3. Ruby: Rayquayza (Age 12)

Emerald: Rayquaza usually lol, I always get impatient haha and I never usually pursue the other legendaries, I've never actually seen Latios/as in-game lol :)

Leaf Green - I don't think I used mine actually but if I did it would've been on the roaming dog, as I picked Charmander it would've been Suicune :)

I usually save my Master Ball for the roaming legendaries. So in Emerald I used it on Latios or Latias, and in Fire Red I used it one of the legendary dogs. The only exception to this is in Red/Blue I use it on Mewtwo.

On Sapphire I used it on Kyogre and on Emerald I used it on Rayquaza. Looking back I wish I had caught them with net balls/ultra balls and save the master ball for Latios/Latias, but I was like 10 and I really wanted to catch them.

In both my Ruby and Sapphire, I used it on the roaming Pokemon respective to that game.
But in Emerald, I never did use it. I caught all the Legendaries I could with Ultra Balls. (Except Kyogre, who I surprising caught in a Dive Ball.) I think it's still in there, actually. :P

I always keep my Master Balls for bragging rights to prove that I didn't use any Master Balls to my friends.