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.
The Strongest of Brothers BT21-090 C While you have a Digimon or Tamer with [Gammamon] in its text on the field, you can ignore this card's color requirements. [Main] Reveal the top 3 cards of your deck. Add 1 card with [Gammamon] in its text among them to the hand. Return the rest to the bottom of the deck. Then, place this card in the battle area. [All Turns] When effects place digivolution cards under your Digimon, <Delay> • 1 of your Digimon may digivolve into a Digimon card with [Gammamon] in its text in the hand without paying the cost. --- [Security] You may play 1 card with [Gammamon] in its text and a play cost of 4 or less from your hand or trash without paying the cost. Then, place this card in the battle area.
The Strongest of Brothers BT21-090 C While you have a Digimon or Tamer with [Gammamon] in its text on the field, you can ignore this card's color requirements. [Main] Reveal the top 3 cards of your deck. Add 1 card with [Gammamon] in its text among them to the hand. Return the rest to the bottom of the deck. Then, place this card in the battle area. [All Turns] When effects place digivolution cards under your Digimon, <Delay> • 1 of your Digimon may digivolve into a Digimon card with [Gammamon] in its text in the hand without paying the cost. --- [Security] You may play 1 card with [Gammamon] in its text and a play cost of 4 or less from your hand or trash without paying the cost. Then, place this card in the battle area.
The Strongest of Brothers BT21-090 C While you have a Digimon or Tamer with [Gammamon] in its text on the field, you can ignore this card's color requirements. [Main] Reveal the top 3 cards of your deck. Add 1 card with [Gammamon] in its text among them to the hand. Return the rest to the bottom of the deck. Then, place this card in the battle area. [All Turns] When effects place digivolution cards under your Digimon, <Delay> • 1 of your Digimon may digivolve into a Digimon card with [Gammamon] in its text in the hand without paying the cost. ---