Q1: If this card has both red and black digivolution cards, can this card's When Digivolving effect delete both Digimon and Tamers?
Yes, it can.
Q2: If this card has both red and black digivolution cards, can this card's When Digivolving effect delete both 6 play cost worth of my opponent’s Digimon, and 6 play cost worth of my opponent’s Tamers?
No. The total play costs of the chosen Digimon and Tamers must add up to 6 or less.
Q3: If a single red and black multicolor card is in this card’s digivolution cards, can I activate both parts of this card’s When Digivolving effect?
Yes, you can.
Lv.6 BlackWarGreymon BT8-070 SR Mega | Virus | Dragonkin [When Digivolving] If this Digimon has a red digivolution card, choose any number of your opponent's Digimon. If this Digimon has a black digivolution card, choose any number of your opponent's Tamers. The chosen cards' play costs must add up to 6 or less. Delete the chosen cards.[All Turns] [Once Per Turn] When an opponent's Digimon is deleted, you may unsuspend this Digimon.
Lv.6 BlackWarGreymon BT8-070 SR Mega | Virus | Dragonkin [When Digivolving] If this Digimon has a red digivolution card, choose any number of your opponent's Digimon. If this Digimon has a black digivolution card, choose any number of your opponent's Tamers. The chosen cards' play costs must add up to 6 or less. Delete the chosen cards.[All Turns] [Once Per Turn] When an opponent's Digimon is deleted, unsuspend this Digimon.
Lv.6 BlackWarGreymon BT8-070 SR Mega | Virus | Dragonkin [When Digivolving] If this Digimon has a {{Colour|red}} digivolution card, choose any number of your opponent's Digimon. If this Digimon has a {{Colour|black}} digivolution card, choose any number of your opponent's Tamers. The chosen cards' play costs must add up to 6 or less. Delete the chosen cards. [All Turns] [Once Per Turn] When an opponent's Digimon is deleted, you may unsuspend this Digimon.
Lv.6 ブラックウォーグレイモン BT8-070 SR 究極体 | ウィルス種 | 竜人型 【進化時】このデジモンの進化元に、赤のカードがあるなら相手のデジモンを、黒のカードがあるなら相手のテイマーを、あわせて登場コスト合計6まで選び、選んだカード全てを消滅させる。【お互いのターン】[ターンに1回]相手のデジモンが消滅したとき、このデジモンをアクティブにできる。