Some close calls...

I can't remember any exact battle scenarios that were close calls(I know there were some), but my closest call that I still remember was my first playthrough of soulsilver and I got to Articuno, but forgot to save before I battled it. I weakened it and paralyzed it but still couldn't catch it. I ran out of Ultra balls and all I had left was a Master Ball and one Great Ball. I just knew I was going to have to waste my masterball, but to my surprise I through the Great Ball and CAUGHT IT! Very close call!

A close call I had encountered was surviving my battle against Elesa in Black. My Emolga against her Zebstrika. I had 1 HP left and the Zebstrika had about 40 or 50? And I was like "oh noes imma loooooose :(" I threw it an Aerial Ace attack and BOOM. I got him! The lucky part was that Emolga was my last hope and using Aerial Ace was the best decision I've made xD

I remember during Black's main story I was battling Ghetsis and he was down to his last Pokemon (Seismitoad). I only had Samurott left and he was low on HP.

I commanded Samurott to use Surf and he knocks out Seismitoad! I was so lucky.

I've had maaaany 1HP survival's which every time think is a fluke.

My level 58 Empoleon survived an Earthquake from Cynthia's Garchomp with only 2 HP left and OHKO'd with a critical Ice Beam with Nevermeltice as its held item, I felt like a frikkin rock star after that one.