Angelfish are mostly carnivorous. Bloodworms, daphnia, brine shrimps, shrimps, commercial foods and earthworms make a great dietary menu. Just be sure to vary the food diet and avoid the temptation to stick to only one food.
Angelfish are predators in the wild. Tetras are their natural prey so naturally you should avoid placing with them small fish that can really fit in their mouths. Guppies will not coexist with them especially when the males will have their fins nipped. Deep-bodied tetras such as diamond tetras and then corydoras make suitable tankmates.