WMG / The Mask

The cartoon series takes place in the same universe as Captain Planet And The Planeteers.
The basis for this guess is the shared link of Tim Curry and his characters in each cartoon. We know that prior to her facial scarring and insanity, Dr. Blight was once a good-natured scientist who worked with her lab assistant/husband Malcolm to create a computer AI. After the accident supposedly took Malcolm's life and left her insane, she reprogrammed the AI into her computer MAL and gave it Malcolm's face. What if Malcolm didn't die but had also been driven insane in the accident? Pretorius sure looks a LOT like MAL, after all... and he was never given any sort of history in the series beyond the surgical removal of his own head to plant it onto a robotic body.

The mask can work in the daytime, but only when it wants to.

Remember that Loki's a trickster god first and a night god second. The thing didn't work in Dr. Neuman's office because it didn't want to work at that moment. Come the Animated Series, Loki is all too ready to forgo this rule if it means getting rid of superpowered or ordinary villains. And, hey, he can wind up Lt. Kellaway day and night.
  • This one is pretty solid seeing as it refused to work in front of Dr. Neuman several times in the cartoon.
    • Addendum to the above:

The Mask (or should I say Loki) creates several of Edge City's more outlandish villains
Since wearing the Mask effectively puts Stanley into god mode, defeating ordinary crooks is easy. When he's not using the Mask, it exerts its powers more subtly by rewriting real physics into Cartoon Physics and imposing the result upon selected targets (Terrible Two; Kablamus; etc.). This is more to provide a challenge than anything; it also stops Loki from getting bored. It might have something to do with Edge City already being somewhat unhinged—the madness amplifies the Mask's powers.

Why Walter is so effective against Mask wearers.
The Mask makes the wearer into a Trickster. Most Trickster-types revolve around what would make others laugh at the victim's suffering. But if someone shrugs off a prank or joke, it just isn't very funny anymore. Walter has no emotions to exploit, so Big Head/The Mask can't fight him off as easily as other enemies.
  • It fits with the mask not doing anything when Walter puts it on, too. His lack of imagination/feeling/whatever makes him anathema of the Mask.
    • Actually, the mask doesn't do anything when Walter tries it because it's too small to fit his face.
      • And yet the mask is able to stretch and cover the wearer's whole head (at least in the movie and animated series).
      • The lack of imagination angle makes much more sense(and the "it won't fit" thing was never solidly defined) considering that, in the Kablamus debut episode, Stanley changed his life and became more assertive, only to find the mask no longer worked because he'd lost his repressed side in the process.

It isn't Heroic Willpower that allows Cartoon Stanley to be a hero, but being such a goody two-shoes.
The popular theory for the cartoon is that the Mask is a hero because Stanley has enough Willpower to keep from becoming too violent when under the effects of the mask, as opposed to most other people who put it on. This is one possibility, but there's another that, while depreciating of Stanley, seems to fit him more.

Normally, the Mask would bring out one's darker impulses. Even an upstanding citizen likely has a repressed dark side, dark thoughts on what they'd like to do if unimpeded by laws or rules. The Mask often brings these dark thoughts out to the forefront. Some people can control these urges through incredible willpower. For Stanley, however, it's not willpower, but his own soft nature. Basically, he's so soft-hearted that he never had such a dark side. He could never imagine himself 'cutting loose' like most other people would end up doing as the Mask. Oh, he acts all wild and chaotic and is a thorn in the cop's side, but he never does anything truly evil. Indeed, even when supposedly unimpeded by morality and laws, he still goes to the effort of doing the right thing and saving the day.

The reason why Tina isn't in the animated series is because her and Stanley's relationship sadly didn't last.
This is one question that's plagued quite a few of the fans' minds. It's all but confirmed in the first episode of the cartoon that the events of the movie did happen, so where the heck is Tina?!

Well, a while back I was talking to a friend of mine online, and she came up with a theory for Tina's absence from the series that is incredibly plausible:

After Milo gets the mask back at the end of the movie, Stanley is at first stunned and tries to hide it from Tina, as they were now a couple. But after seeing all the crime in Edge City, and the temptation to release his inner desires finally gets the better of him, he always goes off being The Mask. But, Tina doesnt want The Mask butting in between her and Stanley (literally). She confronts Stanley about this, and tells him that it's either her or The Mask. Stanley says he can't just leave the city to the crooks, so Tina decides to leave him and pursue her career as a singer, while he is left as being the crazy vigilante.

And the reason why Tina is never mentioned in the series? Simple; their break-up is still a sore subject for Stanley, and he doesn't like talking about it.