3 official rulings from Bandai, last ruled Sep 6, 2024. Straight answers to how this card actually resolves.

Can I use this card’s <On Play> <When Digivolving> effect to place just 2 cards in digivolution cards when I have 4 level 5 or lower [Argomon] in my trash?
Yes, you can. The effect reads "up to 4," therefore you can place any number from 1 to 4.
Ruled Sep 6, 2024
When I use this card's <On Play> <When Digivolving> effect to delete up to 4 levels' worth of Digimon, can I delete my opponent's "Lv.-" Digimon?
No, you can't. "Lv.-" Digimon don't have a level, therefore they can't be chosen as targets for an effect that deletes up to 4 levels' worth of Digimon.
Ruled Sep 6, 2024
BT17-048 [Argomon] was deleted while it had an [Argomon] with an <On Deletion> effect in its digivolution cards. I first used BT17-048 [Argomon]'s <On Deletion> effect to play this card. At such times, if I use this card's <On Play> effect to place [Argomon] in digivolution cards before activating the <On Deletion> effect, what happens to that effect?
If a card is removed from the trash before a triggered <On Deletion> effect activates, that <On Deletion> effect can't be activated.
Ruled Sep 6, 2024
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