Pokémon Food (sometimes refered to as PokéFood or PokéChow) is special kind of food made specially for Pokémon. It was introduced in the Pokémon Anime, as an possible explaination for what Pokémon eat (before the introduction of Berries). It basically comes in the form dry food pellets (similar to real world dry pet food) made (from a varity of ingedents including Berries) to fit a Pokémon dietry needs. Pokémon Breeders often specialize in making food that is both healthy for and that pokemon find tasty.
Despite being made for pokemon, some humans (Pokémon Trainers & Pokémon Breeders) have been shown consuming one of these food pellets (usually in order to evaluate its taste or texture) with no ill effects. It is unknown if it is dangerous for humans to consume larger amounts of Pokémon food.
Brock is shown quite talented cooking & creating various Pokemon Food blends.