It depends on the context. Just scaling a npc is not really satisfying. You should add something which requires a new strategy to approach the enemies other then hitting the attack button more often.
E.g. an elite version of a npc should have some extra feature/skill the standard version does not have.
Taking your example, a standard goblin has almost no armor, whereas a champion is armored (choice of other attack spells) and an elite goblin is able to call reinforces.