From the tags:
"Someone Copies Johnny Quest?" Y tho"
This brings up an interesting point. Serial number filing isn't about copying, not exactly. It's about storytelling, inspiration, and transformative work.
The series in question is the Venture Bros., which is more of a golf-bag pastiche than a direct serial-filing, but these things are always in gradients. The Venture Bros jumps off from Johnny Quest's general concept as a starting point, as a way of commenting about Johnny Quest and the Hanna-Barbera Adventure age, and the people who grew up with it. The general premise is "What if Johnny grew up and was a burned out former-child star-type", with now Dr. Rusty Venture filling the grown-up Johnny Quest role.
But for another take on the Johnny Quest formula, you have the Secret Saturdays, which was more the approach of "I loved Johnny Quest as a kid, what if I replicated those tropes, tones, and archetypes for a new generation?" I'm very familiar with this impulse, as its the driving force behind my whole "deal.""
Neither approach is theft in any meaningful sense. The goal of the first is to extrapolate and expand on a concept in ways the original text did not. The second is the process of creating genre from foundational work.
You could accomplish either with official spinoffs or reboots, but most of the time you can't get those rights (Star Wars happened because Lucas couldn't get the rights to do Flash Gordon), or if you could, the realities of the market mean that you idea won't be viable (Sorry Alan, but we just bought the Charlton guys and by the end of your story they're all dead or psychologically broken). Or maybe the original thing actually wasn't that good, but you could make it so much better (Arguably the Dial-H-for-Ben-10 situation).
All of which is how people have created and told stories, and by people, I mean multiple clades of humans. This is pre-homo sapiens stuff.
One of the inspirations for this post is the elderly Scooby Gang post wandering around the Tumblrs. Just... change their clothes and names. They can still have been mystery teens as kids (HB made about a dozen shows int he genre on their own), people will get enough of a nod to know who is supposed to represent who. Make it into a webcomic or visual novel or whatever, and let your story breathe.
If you're gonna make a Pokemon Argon/Neon or whatever, just paste over the canon pokemon you were going to keep with more interesting fakemon, change the names and visual iconography, call it "BioCritter Adventure" or somesuch. Let your ideas diffuse into the gaps left by removed canon. I guarantee you there's more flagrant knockoffs by major corporations.