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, Link, or Assembly requirements. 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.

No, you can't. A "by" condition can't be met if only some of the required actions are performed. The conditions for this [When Digivolving] [When Attacking] effect require you to place the specified number of cards in digivolution cards.