The main cast of the core Super Mario Bros. games are actors playing roles (Super Mario Bros. 3 gives away the game). This is why Super Mario Land and Super Mario Bros. 2 play differently: Tatanga and Wart aren't in on the kayfabe and think the whole thing is real, so Mario (and the gang, in 2) have to go beat their asses for real.
"Are you kidding me," Mario grumbles as he looks at a map of Sarasaland, "this fucker actually kidnapped Daisy?" Bowser and Peach look on, incredulous.
Ninji approaches Bowser while Shyguy and Birdo look on. "Listen, this Wart guy's a dick-"
"*And he won't pay for HRT or GRS!" Birdo shouts.
"...anyway, can we join your troupe? Shyguy over there won't tell you, but they played Trigorin in The Seagull at Wesleyan."
