I noticed some of the Team Rocket cards have pokemon powers when played from
hand.... means?Can you use the pokemon power from your hand?Or do you have to
evolve the pokemon in order to use this pokemon power?

Well, we'll blame WotC again for another poorly worded card (you Magic people understand this well).

the cards that have a Pokemon Power that is "played from your hand" (reference Dark Dragonite & Dark Slowbro, and Dark Golbat for example), this means when you bring the card into play from your hand.  This does NOT mean that you can use the Pokemon Power while the card is in your hand, though I can understand why some of you might have thought that since they are worded somewhat poorly.

Scott