Alright, this works best on a flat level, like Final Destination. Have Jiggylpuff towards the edge. The have Pikachu Jump off. Make Pikachu use it's recover jump and go through Jigglypuff. Now, right before you get to Jigglypuff, have Jigglypuff use Sing. If Done correctly, Pikachu will fall asleep and slide across the field.
I found this out when I was trying out jigglypuff and I tried to do the move where Jigglypuff goes to sleep and accidently used sing. XD