Smashboards

Jigglypuff will likely have pretty polarized matchups; no good way to force an approach and a significant weakness against both shields and options immediately out of shields (roll backward/attacks OoS) suggest that unless Jigglypuff camps hardcore or develops her edgeguarding game significantly, she'll be a useful pocket character, but little else.

Wario overcomes a lot of those problems; a more substantial ground game, a pretty safe command grab, the ability to heal via eating items/your Bike, and the obscene power of Waft. His ability to approach is somewhat limited but he can do a lot with individual hits and has the tools to work reactively rather well. He'll likely be a reasonably strong character this time around.

I can understand that about Jiggs. I noticed majority of the stocks you took were due to gimps and somewhat early deaths. Having a great edgeguarding game with her would allow her to excel, but she does seem like a good pocket char to have as not many actually understand the matchup.

I'd say both characters need to play reactive most of the time. With Jigglypuff and patience, hang out near/on the ledge and get comfortable working from there. Wario should focus on staggering the opponent with weak moves like F-Air, D-Tilt, and Jab in order to get slight frame advantage. That's how you get in.
Wario has a lot of good moves he can "just stick out" in a defensive manner, like Neutral-B and his tilts.

Wario seems like a great char to pick up. It's how to actually go about playing him is my biggest concern. I heard that his ground game compared to brawl is much better, but his aerial mobility/gameplay has been decreased significantly. How useful do you find using the bike? Combo potential?

The main problem with Jigglypuff is that you can't really do much if the opponent decides they don't want to fight. You have nothing to punish backward rolls reliably, and your pokes are not very fast. Dancing around opponents' shields is alright, but a lot of characters can swat you mindlessly without much trouble.

That said, she's great against people who arent used to the matchup, yeah. Strong punishes.

Rising F-Air and Neutral-B (rising, falling, anytime!) are really good for breaking the ice as long as you retreat as soon as possible once you see a whiff. Jab and F-Tilt are bigger and safer than in Brawl, and roll-cancel grab is nice for people trying to space just outside of your attack range. Dash Attack is deceptively solid for pokes and catching landings.

Wario N-Air has a huge gap between sweetspot and sourspot hitboxes now so it isn't nearly as good as it was. D-Air no longer autocanceling is unfortunate but overblown as an issue; it's a good KO move now, at least. He can't weave as well so airdodging like an idiot isn't as good, but he should still be able to camp well, especially with the Bike changes.

(If I wasn't clear, two posts up is about Wario; please don't use Rollout in neutral, hah.)