SoulSilver, going against Suicune.
My Glaceon starts with Ice Beam and brings Suicune to the red zone. Next turn I use Hail, and it's HP goes to 1(empty spot in party). Suicune luckily saves itself by using Rain Dance. 30 Minutes and 50 Balls later, I finally trapped it in a quick ball that I had left. Kinda lucky, but it gets better.
Normally, I don't save after catching a legendary because I don't generally use them, and I like listening to the epic battle music, but this time, I decided to save. The next day, I decided to check Suicune's stats and I saw why.
It's nature is Bold, so it's defense gets a boost, which is really awesome for a poke with already high defense. Since Suicune is not an uber, I am really considering it for my competitive team. The only way it could have been better is if it's Hidden Power was Electric (for the oh-so common Gyarados), which is actually grass. But I can still use it for the Water/Ground typing.