Ruling Holon's Cards Questions

[Elbow]

Say I have Porygon as my active pokemon, and I attach Holon's Voltorb to Porygon.
May I replace the Voltorb with Holon's Castform or an energy?
Im trying to play older decks and am confused on how the mechanic works, thanks in advance though!
EDIT: Does any poke-energy card count as an energy attachment for the turn?

 

[Elbow]

Anyone?
I'm dying to play Flyvees

 

[Brave Vesperia]

You may replace Voltorb with Castform.

Both Voltorb and Castform count as an Energy Attachment.

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Posting again to clarify that:

Voltorb goes back to your hand after attaching Castform.
Voltorb and Castform can not be attached in the same turn because attaching one counts as your attachment for the turn.

 

[Elbow]

Thanks!