Dimetromon

Q:What order do a [Security] effect, "when [...] performs a security check" effect, and "when a card is removed from [...] security stack" effect activate when they trigger simultaneously upon a security check?

A:[Security] effects take precedence for activation. Upon a security check, a [Security] effect will immediately activate without pending activation. For other triggered effects, the turn player activates their effects first.

Q:If this card is checked from a security stack, does its [Security] effect activate, then does it battle with the attacking Digimon?

A:Yes, its [Security] effect activates, then it battles.