Nice!
I agree with your opinion. This IS possibly the greatest song and challenging trainer battle in the Pokémon franchise. I would prolong the fight just to listen to it again and again.
Your arrangement is good, and I like the added bit from the pre-battle dialogue scene. However, it's a little too ambient and looses the original intensity. It needs a deeper bass-line added. Several of the samples create a static sound at certain points, which needs looking into for future pieces. The pre-battle dialogue music could have transitioned a little better, too.
Great piece, though. Keep up the good work!