

Q1: There are two copies of this card in the battle area. Can I activate both of their Main effects and play or use one specified card with its cost reduced by the combined amount from both effects?
No, you can't. You can't simultaneously activate multiple effects that play or use a card.
Q2: If a Digimon with the effect "Players can't reduce play costs," such as ST12-03 Solarmon, is in the battle area, can I activate this card's Main effect and play a specified card?
You can activate it and play the card, but the cost will not be reduced.
Q3: If a Digimon with the effect "Players can't play Digimon by effects," such as BT9-047 Pomumon, is in the battle area, can I activate this card's Main effect and play a specified card?
You can activate it, but the card can't be played.
Lv.4 Manekimon BT26-012 C Champion | Vaccine | Puppet/Shambala/TB [Main] [Once Per Turn] You may play or use 1 [TB] trait card from your hand with the cost reduced by 2. --- [When Attacking] [Once Per Turn] 1 of your opponent's Digimon gets -2000 DP for the turn.
Lv.4 Manekimon BT26-012 C Champion | Vaccine | Puppet/Shambala/TB [Digivolve] Lv.3 w/[Shambala] trait: Cost 2 [Main] [Once Per Turn] You may play or use 1 [TB] trait card from your hand with the cost reduced by 2. --- [When Attacking] [Once Per Turn] 1 of your opponent's Digimon gets -2000 DP for the turn.
Lv.4 Manekimon BT26-012 C champion | Vaccine | Puppet/Shambala/TB [Digivolve] Lv.3 w/[Shambala] trait: Cost 2 [Main] [Once Per Turn] You may play or use 1 [TB] trait card from your hand with the cost reduced by 2. --- [When Attacking] [Once Per Turn] 1 of your opponent's Digimon gets -2000 DP for the turn.
Lv.4 マネキモン BT26-012 C 成熟期 | ワクチン種 | パペット型/シャンバラ/TB 【メイン】[ターン1回]自分の手札から、特徴「TB」を持つカード1枚を支払うコスト-2で登場/使用できる。 --- 【アタック時】[ターン1回]ターン終了まで、相手のデジモン1体をDP-2000。