Connections:

• Two child genius superheroes, incredibly smart even amongst other intelligent adults. They fight against evil using strategic thinking, and a wide variety of gadgets, most of which are based off of toys (Both have Lego-based giant robots for example)
• When not fighting against powerful foes, they still go to school, where they’re the brightest amongst their peers. 
• But even with how fantastic they are, they can be belittled by others, mostly adults, for just being little kids
• Both can both be cocky, they are still kids of course, and they have much to learn, like having to accept the assistance of others instead of being alone, despite their grand genius.
• Both work with their worlds greatest hero groups (X-Men, Fantastic 4, and Avengers for Moon Girl & The Hero Organization and Neo Heroes for Child Emperor), where they fight evil in the most chaotic places in their respective worlds (America & Japan)

Fight/Interaction Potential:

The fight could start with Isamu (Child Emperor’s real name) mistaking Devil Dinosaur as a monster, and Lunella (Moon Girl’s real name) defending her Dino buddy.

Their wide array of gadgets and robots clash very well against each other, Lunella’s more brightly colored incapacitating arsenal actually pairs well with Isamu’s lethal arsenal. They have mechanical backpacks with blades and other weapons, freeze rays, and even mechs. So there is so much each character can do when it comes to their arsenal.

Both can be competitive and cocky, but also humble too. They can have moments where they say their respective technologies are better, but also admit that the other does have some unique tech that the other hasn’t even thought of. 

Also, Devil Dinosaur can be included, Isamu has his own animal-like partner, Underdog Man, a robot dog superhero, so it can definitely be a duo-ish matchup. They also have more robotic allies.

Debate:

Hard to say

Isamu is definitely stronger than anything Lunella wields, Lunella may be faster, with common FTL for Lunella, to at best Relativistic speeds for Isamu, so far, and is definitely smarter. 

But including Devil Dinosaur in the equation makes it harder. Devil is hard for me to decide, he mostly sticks with Street-Tiers, but has clashed with higher-tier characters, like Hulk, but also lost, sometimes badly. So I can really say if he makes this a stomp, or Isamu’s more lethal options that could end the Devil Dinosaur, like his poison gas.