How to switch stances with Aegislash?

Question

I'm about to use my Sand Team in Showdown, but I don't know how to change stances, can someone please help?

Answer 1

You need to have a move called King's Shield to change stances.

To change to shield form use King's Shield. To change to blade form use a damaging move.

To the left is blade form and to the right is shield form

Answer 2

Aegislash changes stances in two ways.

Aegislash is sent into battle in its Shield Form. To convert Aegislash to Blade Form, use any attacking move. His Attack and Special Attack will rise and his Defense and Special Defense will fall. To revert back to Shield Form, use the move King's Shield. Only King's Shield will activate Aegislash's Stance Change back to Shield Form. Protect will not make Aegislash revert.

http://www.serebii.net/pokedex-xy/681.shtml

Answer 3

It changes it's form based on attack. Direct contact moves (moves that it uses to damage not through status issues and things related to status issues) will revert it to Blade Form, and moves that do not do direct damage (or none at all) will revert it to Shield Form.
E.g Aegislash uses Shadow Sneak, it will become Blade Form, next turn, it uses King's Shield, it becomes Shield Form. It changes forms before it uses the selected move.

Hope I helped