Got a very good Jigglypuff secondary in my area so I have a slight amount of MU experience against her.
First all, NEVER pick a large stage or a stage where you can move through the floor like Halberd and Delfino. If Jigglypuff has a % lead, it'll be very difficult to win because she can just float around the stage and cancel your Din's with multiple moves. In the end, you'll be timed out and mentally exhausted. If you have the % lead, be cautious because Jigglypuff has some pretty decent spacing moves.
Don't be greedy, not one single bit. Do whatever you can to avoid taking damage. Jigglypuff can EASILY punish a Zelda up smash. Up smash will either ruin you, or it'll win you the match if the opponent doesn't have a clue about that move (try not to use this skill too much imo). You should capitalize on punishes, though this will be hard with her aerial mobility. Jigglypuff has a very bad ground game, so stay grounded yourself where Zelda excels. Use fair/bair only as a retreating move. Zelda missing her up air is very punishable. Nair is probably good for platform pressure, but that's it?
Never approach Jigglypuff when she's using Sing on the ledge (this shouldn't be used though). The ledge cancels her sing, and makes you an easy target for Rest/fair. Rollout lasts longer than you'd think, and the final part of Rollout still can kill Zelda at early percents. While Rollout seems easy to deal with and pathetic, it seems to land more than you'd think. Nayru's Love isn't always effective against it. If there are platforms, take advantage of that.
Pound is an approaching option for Jigglypuff. Be careful, the hitboxes last and extend longer than you'd think but it also makes her punishable with a Fsmash (you'll be grounded).
Jigglypuff has a DACUS on the ground so try to learn the range of that move. If for some strange reason Jigglypuff stays on the ground and retreats slightly, expect a DACUS. Jigglypuff's own fair/bair can be a Wall of Pain can make it difficult to recover. Love jumping might help you escape this... the problem is Jigglypuff's up air can juggle. If the dair is read, Jigglypuff can Sing and punish.
Might add more stuff later... Good luck! <3
Edit: Here's a 2 in 1 video for:
Riot and Ed!
http://www.youtube.com/watch?v=Yfk2APQxReo
Fuujin and Ed!
http://www.youtube.com/watch?v=vFdZ8fXvciY
Ed!
http://www.youtube.com/watch?v=AFkJUb_-csc