I love these ideas, but they have lived at home for too long. Time to go out into the real word.

Elemental Lords

Summary: As if keeping track of 16 realms was hard enough, now there are parallel universes too? The ninja meet their doppelgängers from another universe, but something seems off about them, not to mention they call themselves the Elemental Lords. Not suspicious, nope not at all.

Plot similar to Justice League Justice Lords episode - A Better World. In this universe, Jay is killed by the enemy, and the team loses their light. Nya is scary.

Switched

Summary: The classic body swap trope.  Bonus points for broken up jaya (between season 3-6).

Opener: When Jay woke up, the farthest thing from his mind was battle strategizing for the upcoming day.  Tailing XYZ villain and his cronies was turning out to be a lot more effort than anticipated. Camping in the forbidden forest with all the guys was not as fun as Master Wu made it out to be.  Too many creepy sounds and shadows for his liking. At least the rest of the team shared the same sediment. That and they were all slightly annoyed that the girls got to go to a lavish hot spring to chase down their leads. Not that he minded sleeping on the hard forest ground, but he missed his bed and a certain warm soft body that he could cuddle with.

Covergirl

Summary: Nya and Skylor pose for a magazine for charity. Should have known there would be unintended consequences.

Re Jay and Kai being mad: Jay looked like he was about to cause a city wide blackout followed up by Kai burning the whole city down.

Bitter Memories

Summary: (HC from @Dissmisery)  When they first started dating, Nya was fascinated (and fangirled over) Jay's lightning. So, the guy did the heart thing with his fingers (you know, crossing your thumb and pointer to form a heart shape) to let a spark in the shape of a heart come out of it.

The heart thing was obviously Jay and Nya's signature thing, but when they broke up, she saw a photo of Jay on a magazine doing the exact same trick for all the fangirls so she gets really upset because it was supposed to be their thing.

Opener (flashback to season 1 or 2):

"And then, you pinch your thumb and pointer finger together like this," Jay explained as he made a fist then crossed his thumb and pointer finger, forming the shape of a heart. 

Nya mimicked his movements.  "Like this?"

"Yeah, like that." Jay smiled as he inspected her technique.  "And if you want to be extra-"

"Phsss, that's just you," she cut him off and he shot her a scowl.

"As I was saying, if you want some extra flare, you can do this."  His hand started glowing a telling blue, then lightning slowly arched around the silhouette of his pinched fingers, forming the shape of a heart.

"I think only you can be that extra," Nya murmured, mesmerized by the mini-light show.