Multivitamins and fish oil are very good options for overall health, but they'll have very little positive or negative impact on your weight.
Protein supplementation is good if you're not meeting your protein needs as it is, so you'll want to check to see if that's the case with you, since most North Americans well exceed their daily protein requirements. However, most successful weight loss programs involve a moderate decrease in carbs and fats and an increase in protein intake, so if you do need more protein, powders are fine.
Creatine isn't really going to do much for you. People take creatine in order to bulk up, not lose weight. In fact, it causes you to retain more water, so by using it, you'll likely see a sudden increase in weight. None of it is fat, though, so if you want to still take it to be able to lift more, then go for it.