Do I have to activate this card's [When Attacking] effect?
No, you can choose not to use it.
Mar. 28, 2024
I attack with this card, and use its [When Attacking] effect to play [MaloMyotismon]. When this Digimon is deleted after this, what happens to the attack?
The attacking Digimon was deleted, so the attack ends. However, other "when one of your Digimon attacks" effects and effects activated at counter timing are activated before the attack ends.
Mar. 28, 2024
I attack with this card, and use its [When Attacking] effect to play [MaloMyotismon]. Can I then activate any [When Attacking] inherited effects on this card?
No. After this Digimon is deleted, its other [When Attacking] effects can't be activated. You can, however, activate other [When Attacking] effects prior to activating this card's [When Attacking] effect.
Mar. 28, 2024
I attack with this card, and use its [When Attacking] effect to play [MaloMyotismon]. This Digimon is then deleted, but do I gain a memory from [MaloMyotismon]'s "[All Turns] When another Digimon is deleted, gain 1 memory" effect?
Yes, BT3-92 [MaloMyotismon] is in play when this card is deleted, so you gain 1 memory.
Mar. 28, 2024