

Q1: Can I use this card's Main effect to place this card as the bottom digivolution card, and then play a specified card?
Yes, you can.
Q2: If this card doesn't have digivolution cards, can I activate its Main effect?
No, you can't activate it.
Q3: This card only has Digi-Egg cards in its digivolution cards. Can I activate this card's Main effect?
Yes, it can be activated. After activation, you place this card under the Digi-Egg cards, then you can play a specified card. However, if the top card is now a card that doesn't have DP, it will then be trashed by rule checks.
Q4: This card only has a card with 1000 DP in its digivolution cards. If another effect reduces the DP by 1000, can I activate this card's Main effect?
Yes, it can be activated. After activation, you place this card under the digivolution cards, then you can play a specified card. However, if the top card's DP is now 0, it will then be deleted by rule checks.
Lv.4 Greymon BT23-008 U Champion | Vaccine | Dinosaur/CS <Raid> [Main] [Once Per Turn] By placing this Digimon's top stacked card as its bottom digivolution card, you may play 1 [Gabumon] or [Nokia Shiramine] from your hand with the play cost reduced by 2. --- [Your Turn] This Digimon gets +2000 DP.
Lv.4 Greymon BT23-008 U Champion | Vaccine | Dinosaur/CS [Digivolve] Lv.3 w/[Agumon] in name or w/[CS] trait: Cost 2 <Raid> [Main] [Once Per Turn] By placing this Digimon's top stacked card as its bottom digivolution card, you may play 1 [Gabumon] or [Nokia Shiramine] from your hand with the play cost reduced by 2. --- [Your Turn] This Digimon gets +2000 DP.
Lv.4 Greymon BT23-008 U champion | Vaccine | Dinosaur/CS [Digivolve] Lv.3 w/[Agumon] in name or w/[CS] trait: Cost 2 <Raid> [Main] [Once Per Turn] By placing this Digimon's top stacked card as its bottom digivolution card, you may play 1 [Gabumon] or [Nokia Shiramine] from your hand with the play cost reduced by 2. --- [Your Turn] This Digimon gets +2000 DP.
Lv.4 グレイモン BT23-008 U 成熟期 | ワクチン種 | 恐竜型/CS ≪突進≫ 【メイン】[ターンに1回]このデジモンに重ねられているカードを上から1枚このデジモンの進化元の下に置くことで、自分の手札から、「ガブモン」/「白峰ノキア」1枚を支払う登場コスト-2で登場できる。 --- 【自分のターン】このデジモンをDP+2000。