I think Jiggs is a speed because people who are good with her use her jumps to get her across the stage faster than any other character. Also, her aerial attacks are weak and fast. if you walk across the stage, she is medium. But if you use the jumps effectively, it is extremely fast.

__________________
0173-0974-1865 < Brawl friendcode!4253-4013-1847 < MKWii FC!
{Spur of the moment Toad Mario Kart poem below! lol it is bad!}