Jackie Chan Adventures/WMG

Drago is the son of future Jade and Shendu's good side.
Shendu manages to become corporeal again, regaining the Monkey and Tiger powers. His good side stays at Section 13 while shaped like a human, helping to keep his evil half contained. Considering that he's a demon warlock, instead of being a wimpy do-gooder guy like Jackie's good side, he's just unselfish and with morals not obscured by the demonic aspects of his personality. With future Jade as head of Section 13, you can see where this is going.

Tony Stark based his repulsor-firing in the Iron Man film on how the Dragon Talisman is used in this show.
Look at the way the Dragon Talisman is wielded, then compare with how Tony was using his repulsors in the film. It matches more than needed for a coincidence...
 * He's a fan of the show?

Uncle really is everyone's uncle.
Even yours. ☺
 * Alternatively, his name might be An-Kou Chan, uncle being the nearest he could pronounce. And he's embarrassed to have a name that sounds that feminine (at least the An-Kou part - sounds a lot like Anko; if a Japanese knows that's his true name, his pride is obliterated to ashes).

Uncle is nobody's uncle.
He's everybody's Honorary Uncle. And may have been so to Jackie's ancestors for generations.

Uncle's name really is "uncle".
He even calls himself uncle.

Astral Projection, Balance, and Motion to the Motionless are the recipe for creating a clone army and becoming immortal.
Use the sheep power to move out of your body, tiger/balance to duplicate into good (which will have no mind anyway) and evil (again, no mind, so only the body splits), then after doing this as many times as you want, use the rat to bring the duplicates to life, and move back into one after the battle. Caveats: Only works with the intangible powers, not the talismans, and if all your bodies die, you die. Horse and dog are unnecessary.
 * Other caveats include: the Tiger talisman divides itself when used in anyone but Shendu(if it has any effect at all on him) and the Rat talisman does not work on more than one thing at a time.

The real Jackie Chan really did have all these adventures.
This all is based on real life events that secretly happened to Jackie Chan. Everyone else who witnessed these events had their minds scrubbed. (Yes, that's why you can't remember where you put your keys, too.) You might be wondering: If it's all supposed to be so secret, then how come he's got a cartoon about it? The answer? Nobody takes cartoons seriously, anyway!
 * Can I have your attention everyone. Please look into the little red light. Thank you.
 * Alternate theory: Taking the Hollywood episode into account, the real Jackie Chan (real name Chan Kong-san) took the name after first coming to America to star in action movies.

Jade was secretly being used as a Section 13 'special project'
Two sides to it:

1) Once the government learned of just what Jade was capable of, they secretly used Section 13 as a testing ground, allowing Jade to expose any overlooked flaws in newly designed security systems and such before fully implementing them.

2) The government thought that by allowing Jade and her incredible spy aptitude to be exposed to the right environment at an early age, it would eventually allow her to become an unrivaled super agent (kind of like the JCA version of Project Christmas). Which, if her future as director of Section 13 still comes true, actually worked.
 * Sounds like someone has been reading the Evil Overlord List
 * Secret nothing. We see Jade sparring with Section 13 agents in season 2. They've been grooming her to be a special agent since at least the first season.

Jackie is related to Charlie Chan.
He comes from a long line of ass-kicking detectives.

Jade is the Chosen One, and Tohru is her Champion.
In the episode "The Chosen One," some monks mistake Tohru for the reincarnation of their leader, the Chosen One. (Turns out it's Jade.) They also think that Jackie is the Champion. But they were wrong on both counts. Jade is the Chosen One, and Tohru is the Champion.

Tohru states in that episode that he enjoys serving others. Part of the Champion's duty is service. He also is very protective of Jade and willing to give his life to protect her. The Champion is also the protector of the Chosen One. Jade and Tohru share a very close friendship. Only natural, given the roles of Champion and Chosen One.

That's why the monks mistook him for the Chosen One in the first place: they sensed that something was special about him and assumed that meant he was the Chosen One. In reality, he was the Champion.
 * That explains why the magic walking stick hit Jackie when he tried to summon it. He's just a mere mortal so the stick rejected him.

Section 13 is working on a Subspace Transport via Ansible-Interactive Radiation system.
Only certain people such as Captain Black are authorized as test subjects, due to the new and not-fully-tested technology. They placed one transport point at the top of Section 13, one at the main area of Section 13, and targets at high-interest points across the city, which is how Jade and Captain Black were able to use the S.T.A.I.R.S. to get to the Section 13 HQ and Uncle's shop before Jackie. This is never mentioned again because the S.T.A.I.R. system has unpleasant side-effects that increase with use, and testing was discontinued around the end of Episode 2.

Valmont's Villain Decay was almost(?) entirely a result of a Villainous Breakdown in response to having lost his chance at regaining his fortune one time too many.
When a gentleman is accustomed to a certain lifestyle, the idea of becoming a hobo thanks to the failed machinations of the ghost of a dragon statue would tend to wear on his sanity. When one's sanity is compromised, one's villainous panache and effectuality tend to follow.

El Toro is Paco's father.
That's why Paco is always following him around. He calls El Toro by his wrestling name because he's just that much of a wrestling fanboy.

Neither version of future Jade from the J2 episodes will come to pass.
At least not as she is portrayed in either episode. In the Grand Finale, Shendu and Drago, along with the talismans are sent into the demon netherworld by Uncle and Tohru. This means, that unless these two are brought back to life somehow, the talismans are out of the picture, which means Jade can’t destroy the donut shop with the Dragon Talisman and get in trouble. Likewise, Drago cannot appear in the future to become the main threat to Section 13, which means he can’t go back in time with Jade and so on.

Ultimately, with the events of the Grand Finale, the two J2 episodes cease to exist in the actual timeline. Though, with the comment from Captain Black at the end of the Grand Finale it would be safe to say Jade will likely still end up an agent someday and may still be captain of Section 13.

Had the series continued there would've been an episode titled "The Rushed Hour"
With Phil La Marr voicing Agent Chris Tucker

Captain Black is from the American branch of the Black Family
Augustus Black doesn't sound that far off after all