Plus, Aegislash also has the Shield.

Ah I forgot about that, but according to the Pokedex, Zacian's sword can go through anything, including Aegislash's shield

Remember the story about a Chinese Peddler with an unbreakable shield and all-piercing spear?

Honedge, too small to hit

I’m like pretty sure that Zacian could probably defeat Aegislash with Behemoth Blade, even when Aegislash is dynamaxed.

Zacian in its normal form is a Fairy type and is weak to the Steel type moves from Aegislash which also has STAB as a Steel/Ghost type. Also it has Kings Shield to lower Zacian's Defense.

So unless Zacian transforms into its Crowned form and become Fairy/Steel type the advantage in the match is for Aegislash

I would assume so, Zacian doesn't really have to do anything other than hold Rusted Sword to start battle in that form

Also, Dynamax would worsen Aeiglash's chance at victory since Behemoth Blade does increased damage to a dymanazed Pokemon

Okay so lets say that Zacian is in his Crowned Form. So its Fairy/Steel. We still have Aegislash who start in the Shield form. Lets say that Zacian can Dynamax. And Aegislash switch Stance each turn. Two of those 3 turns can still be (Possible succesful) Kings Shield. And one of those Three turn something like Flash cannon Iron head or even Sacred Sword.

@APerson573 How would you know that Aegislash is gay?