Generation
The generation option lets you choose generation data to display. As of November 18th, 2016, main series Pokemon is on their seventh generation.
Exclude
The exclude option excludes Pokemon that are classified as whatever is selected.
Forms encompasses For example if 'Form' is selected then it will exclude Pokemon such as Kyurem - Black or Deoxys - Speed formes from the table.
Mode
The mode option prevents Pokemon with double typings to be counted for both type combinations. For example if 'Lax' is selected then Togekiss would be counted as both Fairy/Flying and Flying/Fairy and will only be counted as Fairy/Flying if 'Strict' is selected.
Type
The type option lets you include and exclude Pokemon of your chosen types.