A game I had on Brawl once when I was being introduced to the game (although I had played all the previous versions, and we were using Gamecube controllers, so I knew most of what I was doing) I played as Ice Climbers against Pit. We were pretty evenly matched, although I think that throughout the game I had the edge.
10 seconds before the timer went, we were both on two kills, but I had inflicted more damage to him. I dodged out of the way of an attack, and struck him with a smash move, but just as he was about to fly out of the ring, the timer ended. As the screen slowed down, he actually ended up falling out, which was frustrating.
As it was technically a draw, sudden death started, and I started in on the attack straight away. Neither of us was able to land a proper blow on each other though, until he ended up hitting a smash ball, and I got wiped out by that.
Alright, so it's not a victory, but it's the most evenly matched game I remember right now.