I'm not quite sure who to blame the battle on, Ash or Buizel. For one thing, Ash knew that Kenny would be going with Empoleon, so if he was really serious, he would have gone with Pikachu or Infernape or even Torterra. After comparing their previous appearances, I'd come to the conclusion that Buizel was about the same power level as Empoleon, but I was apparently wrong. That poor little weasel got slaughtered. Hopefully he'll do better in the League.
Well, the battle seemed to stem from the night training (despite the fact that I can't make heads or tails of what they're saying). After Ash was training Buizel, Buizel's Sonicboom was aimed at Empoleon by accident, and that set the two up for the eventual battle. If it weren't for that training, we might have seen some different (better) battle.
I'm wondering what the Infernape thing was. Ash sent out his to watch Flint's, which could be a foreshadow of Flare Blitz? Personally I'm for Blast Burn, but I guess Flare Blitz couldn't hurt either.