My first legendary encounter was an Entei which I ran from (didn't have enough pokeballs at the time and I was trying to save my PP up for VIP). I ended up catching one later on though.
The first Legendary I encountered was a Legendary Egg and quite a while later it ended up being an Articuno. However, my first actual Legendary encounter/catch was a Mewtwo.
My first legendary encounter was a regirock, but I had just joined and had only a few pokeballs. I didn't catch it.
I caught the eggs first. I think one of the beasts was the first I encountered that wasn't an egg, and I ended up not being able to catch it. Still haven't caught them.
The first legendary I encountered was Entei. Lucky I was able to catch it without much hassle. But in all technicalities, my first legendary was the Zapdos I hatched.
The first legendary I got was a Mew that I hatched. Outside of eggs, the first caught Pokémon was Azelf. I do not remember ever running from a legendary, but I may have ran out of Pokeballs on a Mewtwo long ago
If you count the Eggs, then an Articuno (which I've hatched) was my first. I don't count the Eggs, and I try to make it a point to capture every Legendary species I come across that I have not previously acquired. So technically, my first legendary catch was Mewtwo, which took me so much pain and time to find. I did catch "that thing" before it, but I don't believe "that thing" counts as a Legendary species. You do tempt me, after all.
Legendary and Mythical Eggs hatch at Level 40, not Level 10. The Odd and Mystery Eggs hatch at Level 10.
I know. I’m just so lazy and don’t want to level it up. There is not that much people on right now that post.
Doesn't matter; people get around to posting whenever they're online. It's not supposed to be instant.
Caught since my first legend was a egg and they got a 100% catch rate still haven hatched that egg actually so first true legend encounter would be Raikou and I caught that, really lucky catch only needing one ball. Otherwise it would be my Zapdos since I hatched that one a long time ago.
My first legendary hatched from an egg, a Zapdos. As for wild legendaries, Mewtwo escaped my grasp a number of times until I finally managed to catch it... along with a MissingNo and a shiny Hoppip. My luck fluctuates from amazing to terrible on a regular basis.