Drana and Linvala gains only activated abilities. It doesn’t gain triggered abilities or static abilities. Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities; they have colons in their reminder texts.

If an activated ability references the creature that has it by name, treat Drana and Linvala’s version of that ability as though it referenced Drana and Linvala by name instead. For example, if an opponent controls Onakke Javelineer, Drana and Linvala has the ability “{T}: Drana and Linvala deals 2 damage to target player or battle.”

Once an ability has been activated, it doesn’t matter if Drana and Linvala loses that ability because the opposing creature with that ability leaves the battlefield (or, more optimistically, you gain control of it).

If multiple players control a Drana and Linvala, exactly what abilities each of them has can get complex, based on what order they entered the battlefield. However, as none of those abilities can be activated, we won’t waste a lot of your time getting into it.