I think this has to be my favorite Pikachu short. It's rather creative, and colorful, and I think this is the earliest instance of a rescue team that I know of. I find myself enjoying this more than the movie it premiered with because of how simple the story is, and yet it got really intense at its climax. I like the idea of a large tree holding a Pokémon community in it (even a Snorlax), and how they all care for each other. I actually find it funny how Ash, Misty, and Tracey are so oblivious to what their Pokémon do when they're not looking. Heck, that goes for every short. It really makes you wonder.
Also, the music at the beginning is really catchy. I haven't seen it in a while, but I can sing the song without fail (even if it's really cheesy).