Shadowverse Flame

I'm confused on what kind of the deck Arc Ruler, Erde and Himmel used in their respective battles (the part where they used spell cards to change their decks I understand). Arc Ruler and Erde's decks displayed the Portalcraft symbol (same would go for Himmel ), but they used cards from different decks. Wouldn't each of them started out with Portalcraft decks or are they neutral in which they can use cards they want to?

I just hope there'll be time for Light & Hiro to meet soon.

They are unknown to me