Q1: What does a card with "X in its text" refer to?
It refers to a card that contains the specified text or icon in its name, traits, effects, inherited effects, (Rule), digivolution requirements, DNA digivolution, DigiXros requirements, burst digivolve, App Fusion, or Link. For example, a card with Knightmon in its text would include cards with the name DarkKnightmon and cards with the text Knightmon in their effects.
Lv.6 Siriusmon BT21-028 R Mega | Vaccine | Light Dragon/Hero [Digivolve] Lv.5 w/[Gammamon] in text or w/[Hero] trait: Cost 3 <Security A. +1> <Raid> [When Digivolving] [When Attacking] By placing 1 Digimon card with [Gammamon] in its text or the [Hero] trait from your hand as this Digimon's bottom digivolution card, delete 1 of your opponent's lowest DP Digimon.
Lv.6 Siriusmon BT21-028 R Mega | Vaccine | Light Dragon/Hero [Digivolve] Lv.5 w/[Gammamon] in text or w/[Hero] trait: Cost 3 <Security A. +1> <Raid> [When Digivolving] [When Attacking] By placing 1 Digimon card with [Gammamon] in its text or the [Hero] trait from your hand as this Digimon's bottom digivolution card, delete 1 of your opponent's lowest DP Digimon.
Lv.6 Siriusmon BT21-028 R Mega | Vaccine | Light Dragon/Hero {{DigivolveFromTextOrTrait|3|5|Gammamon|Hero}} <Security A. +1> <Raid> [When Digivolving] [When Attacking] By placing 1 Digimon card with [Gammamon] in its text or the [Hero] from your hand as this Digimon's bottom digivolution card, delete 1 of your opponent's lowest DP Digimon.