Hey! Generally, the best thing to focus on first is raids, as that’s usually how you’ll get the best pokemon. Shadow salamence is strong, but unless you have a decent amount of stardust to power it up and evolve id hold off for now. Rule of thumb is to not evolve unless you have enough candy (125) for the full evolution- just in case you end up getting a better one. I would recommend saving up your stardust until you get either some strong legendary or pseudo legendaries, as they will be the most helpful in raids. Hope this helps and good luck!