What beats what. Pick the Pokémon's types, or your move's, and the chart answers.
Its types (up to two)
Pick the type of the Pokémon you're up against, or both of its types.
Hover or tap a square. The row is the attacking type, the column the Pokémon's type.
The game uses the chart from generation 6 on, Fairy included. Each type's own page lists its Pokémon: Types.