Metal Mario is a Mario from the future, an experimental prototype liquid Metal Mario type 1000.

This reminds me of how Dry Bowser was handled after New Super Mario Bros.  Sometimes he's a transformation, sometimes he's his own character.

Tbh I just interpret "separate entity Metal Mario" as a metallic statue/golem of Mario that is alive for whatever reason. Feels like the simplest way to explain him, if an explanation is even warranted at all

Mannnnn Metal Mario's Melee entrance used to scare me as a kid. He just drops then comes to life with that weird ominous music

When I was a kid playing Smash 64, I always thought of Metal Mario as Mario's version of Shadow Link from Ocarina of Time.
We had our own cryptid-like myths about him that I have forgotten the details of now.

My theory is that Metal Mario basically works the same as the Spiderman's venom suit. It started as merely a coating but over time it developed a life of its own.

The idea that he's not Mario actually makes him terrifying. He's just this, silent, cold, eyeless facsimile of our hero. What are his intentions? What is his origin? It's haunting man!

The fact that he is called "rival" in MK7 is kinda crazy
That means Mario knows of Metal Mario's existence and knows he needs to be defeated or at least beaten in some way

I've always joked that Dr. Mario and Metal Mario were a separate entities but one day I, too, realized that Metal Mario kinda actually is. Cool video, nice to see it broken down like that

As a kid I thought it was so cool he was added to Mario Kart 7. It'd be funny to think if the Mushroom Kingdom just happened to have a metallic man that looked just like Mario and made himself Mario's rival.

If I were to come up with a “lore rationalization” for Metal Mario as a separate character, I’d be inclined to characterize him as some kind of spirit inhabiting the Metal Cap whose lending of his power to Mario is what facilitates that transformation, and who subsequently learned to mimic Mario’s shape all on his own from their interactions.

I don’t think this is canon or anything, just, what I’d do if tasked with writing an explanation for that, haha

Facing Metal Mario in Smash 64 was such an amazing experience. The announcer uses a metallic voice, there is no music playing just a rowdy crowd ready for a show down. You’ve made it far into Classic mode at this point. The announcer counts down, then that music hits, so epic!
Metal Mario barely moves when you hit him, he has no voice lines, who or what are you fighting at this point? After you finally get his damage to 200% he’s starting to move, and when you finally send him flying, his lifeless death makes you really think, was that even Mario?

my theory: after Robo Mario was defeated in the Mario Kart Arcade games, E. Gadd refined and upgraded him to become more like the Metal Cap power-up. After still not winning any tournaments, he left to do his own things (or be a useful asset for E. Gadd)

08:15 Ice Mario appears in Mario Kart Tour and has the same robotic voice as Metal and Gold Mario

Ok, Metal Mario's use of bizarro catchphrases like "Papa Mia" make the character downright eerie. It's like Mario, but wrong. It honestly gives me similar vibes to the Cosmic Clone, who has been gleefully chasing/racing Mario ever since Galaxy. I've always wondered what that thing's deal was, too.

4:50 This is an example of "American Kirby is hardcore"; Metal Mario is unsettling in Japan, cool in USA.

I'd like a full game with Metal Mario as a villain, kinda like Shadow Mario

The weirdest thing is Nintendo did this TWICE.
First with metal Mario, and later with gold Mario, who started as a transformation in NSMB2 and later also appeared as a separate character in MK8.

Actually funny that you mentioned pink gold peach of all things but not gold Mario. :D

I used to have the headcanon that Metal Mario and Dry Bowser's appearances in spin-offs are actually Mario and Bowser from the future, who have both reached such power that they are both permanently invincible...

You think Metal Mario is odd?

Wait til you run into Naked Mario, Venom Mario, Liquid Mario and Solid Mario, thats where things get nuts.