3 official rulings from Bandai, last ruled Mar 28, 2024. Straight answers to how this card actually resolves.

Does this card’s <When Digivolving> effect force both players to trash the top 2 cards of their decks?
Yes. Both players must trash 2 cards each, if possible.
Ruled Mar 28, 2024
Can I choose to not return the cards to my hand for this card's <When Digivolving> effect when I have 1 [Guilmon] or 1 card with [Growlmon]/[Gallantmon] in my trash?
Yes, the effect reads ""you may return [...] to your hand,"" therefore you may choose to not return cards to your hand. However, even in such cases, both players must trash 2 cards from the tops of their decks.
Ruled Mar 28, 2024
Can I choose to not return the cards to my hand for this card's inherited effect when I have 1 [Guilmon] or 1 card with [Growlmon]/[Gallantmon] in my trash?
Yes, the effect reads "you may return [...] to your hand," therefore you may choose to not return cards to your hand.
Ruled Mar 28, 2024
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Questions and answers are Bandai's official rulings, collected and translated by the DigimonCardGame Wiki community and reused here under CC BY-SA. Card names and card text are © their respective publishers; Combalo is not affiliated with Bandai.