So, a Zacian or Zamazenta is poisoned in a double battle. Your ally Pokemon tricks a Rusted Sword or Shield over to Zacian or Zamazenta. Would the Zamazenta or Zacian change into Crowned form, or not? Would the poison be removed?
There is a list of items that are immune to any form of in-battle manipulation: Rusted Sword, only for Zacian Rusted Shield, only for Zamazenta If an item meets this signature item check, then Trick and Switcheroo will fail when used by either side; Fling and Bestow fail when used by the holder.
There is a list of items that are immune to any form of in-battle manipulation: Rusted Sword, only for Zacian Rusted Shield, only for Zamazenta
If an item meets this signature item check, then Trick and Switcheroo will fail when used by either side; Fling and Bestow fail when used by the holder.
Source
Firstly, you aren't able to Trick Rusted Sword and Rusted Shield to Zacian and Zamazenta respectively. Second, even if it was possible, then it won't cure the poison.
If a Pokémon is poisoned while not Poison- or Steel-type (such as while affected by a type-changing move or before evolving into a Poison-type or Steel-type Pokémon), it will remain poisoned.
Hope this helps!