I'm sort of working on a video for a few general AT's for Jigglypuff at this point, but I need to sort of develop them a bit further before I can give information on when it works all the time and when it's just a read, or luck. Keep an eye out for that, it'll be really big stuff.
So although I can't detail when it's best to be used, you can do something I like to call a Dash Rest. By Dashing then immediately jumping and resting, you move a great deal forward and leap straight up. Because rest lasts multiple frames, it sort of creates a pillar of a rest hitbox, allowing you to both punish someone in front of you and allowing you a lethal anti-air option. The timing is identical to what would be a jump-canceled rest, if the game allowed it such at thing to happy. Exact usage is being studied, but I'm sure you can get some good rests in at the meantime.
Other AT's for Jiggs that have been covered (by others):
Dair>rest combo you can land at ~20-40%
Resting through opponent's jabs
There's a video for these two, though I forget where the thread is that features it.