Cories, no. They need warmer water than is good for goldfish, and will have problems with the high levels of ammonia the goldfish create.
The best tankmates for goldfish are other goldfish.
The smallest fancy goldfish reach about 10-12 inches in length and need at least a 30-gallon tank for 1 or 2 fish. These might include the bubble-eyes, celestials, shubunkins, and orandas.
Common goldfish, comets, and the larger fancy goldfish will grow to be at least a foot long, with some of them reaching almost 2 feet. You would need at least a 50-gallon tank for even one of these.