SMAASH! Puppy
Smash Legend
It'd be fun if Mario was referred to as Metal Mario on the character select screen if the Metal rule is selected in Special Smash.Easy. Instead of having outlined colors, like with details, it becomes as pure color(but stays the same hue as normal) like in Smash 64.
So Metal Metal Mario does look different from Metal Mario and Mario turned Metal.
But yes, this alone is why I don't see it being realistic anyway. I'd further say a Metal Box Spirit has a better chance(which would keep you Metal throughout the match, outside of KO'd, maybe?), but start you at a small disadvantage for having more weight, defense, and power naturally due to being actually Metal. Currently you can start off as Metal, but it's a short time, so there's no penalties beyond the natural fact you have more weight and lose jump height.