Rulings
Q1: I have this Digimon in play when one of my other Digimon attacks, deletes an opponent's Digimon, and is deleted in return. Do I gain two memory?
Yes, both you and your opponent's Digimon were deleted, so you gain two memory.
Q2: Do I gain 1 memory from this Digimon's effect when a Security Digimon is deleted?
No, Security Digimon aren't considered to be Digimon, so you don't gain any memory.
Q3: When I had this Digimon, another of my Digimon attacked, and both my Digimon and my opponent's Digimon were deleted in the battle. Do I gain 2 memory at such times?
Yes, the +1 memory effect activates twice, earning you two memory.
Q4: My opponent and I both have this Digimon in play. If another Digimon is deleted, what happens?
The effects trigger simultaneously, so the turn player gains a memory first, followed by the non-turn player gaining a memory, returning the memory gauge to its original position.
Q5: If this Digimon attacks an opponent's Digimon and both Digimon end up being deleted, can I gain a memory off this card's effect?
No. This Digimon was deleted, so the All Turns effect doesn't activate.
Data Sources
Lv.6 MaloMyotismon BT3-092 R Mega | Virus | Demon Lord <Piercing> (When this Digimon attacks and deletes an opponent's Digimon and survives the battle, it performs any security checks it normally would.)[All Turns] When another Digimon is deleted, gain 1 memory for each Digimon deleted.
Lv.6 MaloMyotismon BT3-092 R Mega | Virus | Demon Lord <Piercing> (When this Digimon attacks and deletes an opponent's Digimon and survives the battle, it performs any security checks it normally would.)[All Turns] When another Digimon is deleted, gain 1 memory for each Digimon deleted.
Lv.6 MaloMyotismon BT3-092 R Mega | Virus | Demon Lord <Piercing> (When this Digimon attacks and deletes an opponent's Digimon, it performs any security checks it normally would.) [All Turns] When another Digimon is deleted, gain 1 memory for each Digimon deleted.
Lv.6 ベリアルヴァンデモン BT3-092 R 究極体 | ウィルス種 | 魔王型 ≪貫通≫（このデジモンがアタックしたバトルで相手のデジモンだけを消滅させたとき、このデジモンはセキュリティをチェックする） 【お互いのターン】他の自分のデジモンか、相手のデジモンが消滅したとき、消滅したデジモン1体ごとに、メモリーを+1する。