Hyperbole is engaged in the dual processes of giving you his opinion and pretending you care.
Hey, Ilovecheeseandpenis. Let me take this one section by section.
Quotes: The first quote is amusing. For a disembodied head to exclaim "I AIN'T GOT NO BODY!" makes me chuckle. The second quote is not good. We don't yet have any reason to believe that Mario's head is menacing, let alone that it's an understatement to say so, and name-checking the Uncyclopedia meme "Captain Understatement" seems like a pointless attempt to ride the coattails of an in-joke.
Lede: Okay, Mario's head is annoying and pointless. That's funny. It's also "evil"? That's not very funny. Cajek, bless his soul, used to say that "OMG HE'S EVIIILLL" was the worst possible way to write an Uncyclopedia article. I'm inclined to agree. The sentence "He goes berserk whenever people refuse to give him a computer," out of context, is just not funny. I don't know if it's referring to anything or if it's just random words.
Early Life: Except for the joke about Mario's head exclaiming "Press the Start Button to play," this section needs to go away. It just isn't funny to bring King Harkanian, a character from a totally different franchise, into this. And why explain how Mario lost his head? Some things are funnier if you leave them unexplained.
Mario Teaches Typing: This section isn't bad, but it's really a missed opportunity. Surely there's more humor in the idea that Mario's Head, having become somehow disconnected from his body, decided his first priority would be to teach children to type. Children whose parents gave shitty Christmas gifts. Run with it, man! Mock Mario Teaches Typing! Isn't it begging for it?
Destruction of Hyrule: This is really, really lame. I'm sorry, but this is so unfunny that it taints the rest of the article. Why are you doing "videogame mashup zaniness"? It's been done a million times, and it hasn't been funny even once.
Super Mario 64: I don't know if you can really mutate Mario's face with the cursor. I haven't played this title. That sounds more like MarioPaint to me, but maybe I'm wrong. Either way, this joke may need more explanation for the non-Mario-fanboys out there. Similarly, I'm not sure if "taking bites of their snouts" is related to the game or if it's just random shit thrown in for no reason.
Super Mario 64 DS: Ugh. Video game rape? Seriously? That's never funny.
Death: Put plainly, this ain't funny.
Powers and Abilities: It's always sort of weird to put a section after "Death." It's also very weird that Mario's Head was referred to in the present tense until "Death" and now it's referred to in the past tense. Was this article supposedly written as the head was dying? Anyway, this is basically a bunch of zany randomness with no connection to reality. It is, unfortunately, stupid and just not funny.
There's a decent concept in here just crying to get out. Yes, it's weird and kind of creepy that Mario's head appears in video games, completely without a body. Yes, there's plenty of jokes to be made about that.
Every article needs to exist in a universe. And, with virtually no exceptions, that universe needs to be either "reality" or "reality + 1."
But this universe is "reality + whatever." It's reality, plus:
All video game characters exist in the real world.
But they also exist in video games (i.e., the Nintendo 64 exists and it has a cursor).
Video game characters can create the games they appear in.
Video game characters are mortal.
Video game characters can appear at essentially any size (e.g., they can eat nuclear reactors.)
That's too much. You're stretching reality so far out of shape that it's impossible to make a joke, because suddenly anything can make sense. You can't poke fun at something not making sense when anything's allowed to make literally as little sense as it wants to.
It's sort of like this. This joke is funny:
What's the difference between a dead baby and a bowling ball? You can't fuck a bowling ball.
But this joke isn't funny:
What's the difference between a dead baby and a bowling ball? A dead baby can shove a bowling ball up its ass, but a bowling ball can only shove a dead baby up its ass on Tuesdays.
And the reason the second joke isn't funny is that it stretches reality too far out of shape. The first joke is "reality + 1": reality, plus the joketeller is a pervert who thinks it's awesome to fuck dead babies. The second joke is "reality + whatever", and when there are no rules, there are no rules to break, and there's no comedy to be had.
You've really got to tighten down the concept of your article. Like, how about this: "Reality, plus Mario's head is actually conscious and makes decisions." And there you go. That's the only change to the universe. None of this shit about Zelda and battles royale and nuclear reactors. Hell, you'd do better to leave Luigi out of it entirely.
Prose and formatting:
The prose and formatting aren't too bad. You can write in coherent sentences, so that's a plus. I'm not sure about your comic timing, though - the individual sentences don't always seem like they're the beginning, middle, or end of a specific joke.
Two pictures of Mario's head - that's expected, that's fine. A pic from Mario Teaches Typing might have been good. The picture of the cartoon girl in a bikini just feels out of place and... a little creepy.