Welcome to Super Off-Topic World DS.
I use SSBM as part of my argument since I believe its 3D models are detailed re-presented versions of Nintendo characters in some of their classic forms, with Ocarina of Time's characters as our current focus. So, the way SSBM presents Zelda and Sheik is the way I believe Ocarina of Time intended to show us, and the ol' hand-drawn character art can support this. I can let it slide that Sheik doesn't have to be a 100% man, that is, he/she/it/Birdo might as well lack the "Master Sword" and "Deku Nuts" of sorts, which can explain the female-like voicing. But, I still believe Princess Zelda does undergo a magickal transformation thanks to the power of the Triumph Spork of Wisdom and Witness Protection, to yield a more "manly" upper-body and developed biceps. Again, refer to SSBM's (trophy #2 for each character) character models.
Even if we DISREGARD Super Smash Bros. Melee, Princess Zelda's behavior between the two THE GANNON battles cannot be ignored. As Sheik, she seemed much more jumpy and acrobatic, falling from the sky, chilling in high places, jumping off high places. As TEH Purinsesu Zeruda, she portrayed the simple, helpless, slow, immovable-object we been accustomed to defend. YET SHE SIMPLY POWER-WALKS WHILE THE GANNON'S FORTRESS WAS CRUMBLING. What in Zephos' name happened to her ninja-like (REAL ULTIMATE POWER!) reflexes? Was she hindered by her Royal Hylian footwear? And what's with the OH MY ZEPHOS I'M TRAPPED IN A WALL OF FIRE please rescue me Xandir! situations. AREN'T YOU LIKE THE SAGE OF TIME OR SOMETHING I SAW YOU MAKE YOUR OWN DAMN WALL OF FIRE BACK IN FRONT OF FIRE TEMPLE SEVERAL SAVES AGO AFTER YOU TOUGHT ME THAT ROCKIN' OCARINA MELODY THIS SHOULD BE CHEESECAKE FOR YOU!
It's as if Zelda's attitude and athleticism changes *with her body.*
And no, your little DragonBall moment after the final FINAL battle doesn't count for anything.