... was actually hoping for some kind of unexpected twist or witty punchline at the end.

YAAAAAAAAAY PIKACHU DIED

Hey, it was okay! Though there is a LOT you can improve on. The lip syncing was a little off, the audio needs a little clean up (recommend some of the tutorials on this very site for that) but the big thing for me was the quality of the animation.

The characters never really moved at all except for their arms and mouths. Which is okay sometimes, but their posture and stance were always in the same boring, stood upright position. It says nothing about their character, and it brings the animation down tremendously.

This tutorial: https://www.youtube.com/watch?v=b3iOFYXlRG4
explains what I mean in a lot more detail (highly recommend binging on that whole channel actually).

I could criticise you for a lot of other things (although you had a great use of colour and I liked the pace and flow of your animation!) but its better if you start on one thing and improve that, the rest will come later :) hope this helps!