The "easy" corals are the photosynthic ones: Mushrooms, zoos, star polyps, xenia. Basically the ones that grow like weeds usually grow like weeds in most peoples tanks because they have good light, AND being feed phytoplankton.
Once you get into LSP and SPS that is when you need to start feeding a couple times a week the likes of mysis shrimp, silversides, ect. . .
You'd have to tell us a specific coral, or corals before we could tell you. Because half only need light, and the other half need light and food. There are even some that need food only, and no lighting needs. . Some even more that only need filter food but no light or meaty items. .