I've seen one Entei and two Raikou so far. I'm not gonna lie, it hurt having to skip those Raikou. It's one of my favourites.
I've seen one more Entei, but I didn't bother catching it. I have yet to see Raikou or Suicune, but maybe one day.
I have found exactly one Raikou, which I luckily caught, but no Suicune so far. I have found many an Entei though, but I have one already so let someone else find you Fire Doggo.
I found another Entei earlier today, but didn't bother trying to catch it. My poor Pokéball stock is dwindling so much today. Edit: Woah, since when did "Pokéball" autocorrect on here to be capitalized with the accent on the e?
I caught a Suicune! I'm starting to question whether the Pokéball used really matters. If they can be caught in 14-16 pokeballs but break out of 12 ultra balls.
Last time I saw Raikou it ate through like 15ish of my Pokeballs so I'm still pretty salty about that. :v I hope my next encounter with it I'll be able to have less trouble.
I have captured my beloved Suicune. I've also encountered Raikou twice and Entei once... Failed to capture them, however.
The legendary beasts: Raikou, Entei, and Suicune. Speaking of which, I haven't encountered any, let alone catch one.