White Tanooki Mario
Now, how do you like it? This boss has you in a long NSMB field, trying to dodge White Tanooki Mario and setting up traps in hopes of trapping him in a pit - being more a puzzle than a battle as you switch P-switches, provoke thwomps, and steal springs. After you get him into the pit, you jump to the Mushroom Kingdom stage I submitted and fight a regular Mario who has some subtle and not-so-subtle differences from his regular counterpart - more power, longer range projecitles, slightly stretchier limbs for better range, better speed, super armour and quicker attacks being the subtle ones; while the unsubtle ones are an increase in size at pinch mode and two special moves only this Mario CPU can use: (think the items in SMK) a special invincible Star dash move, and a landing earthquake stomp.
To contextualise a hero being a boss, the battle begins with Mario taking an honourable bow before he picks up the leaf.