Against Kaku, Zoro:
- Activated Asura and had a conversation with Kaku
- Destroyed his Amanedacchi and ran towards Kaku while in Asura:
- Zoro executed a counter attack
- Zoro was running around in Asura
- Defeated him with Ichibigun
Zoro performed several actions with his first usage of Asura.
Preskip Asura was much like G3:
- Zoro activated Asura, performed a few attacks, then changed back to base.
- Luffy activated G3, performed a few attacks, then reverted to chibi Luffy until the cooldown expired
Zoro has multiple attacks in Asura:
Luffy had multiple attacks in G3
- Gigant Pistol
- Gigant Whip
- Gigant Bazooka
- etc.
I think Asura is near exactly analogous to G3 (this makes sense, as Asura was Zoro's G3 equivalent). If you consider Gear Third a single move, you should consider Asura one as well, likewise if you consider Gear Third a form.
I think both are forms that grant Luffy/Zoro access to new movesets.