Pokeball

The Pokeball is a device specially made for catching Pokémon. You can capture a Pokémon if it has a red life bar.

Catching Pokemon
Pokémon may only be caught when their health bar turns red. For enemies with green health bars, attacks will eventually lower their health into the red zone. Also, the wild shiny Pokémon and the Legendary Dogs ( Entei, Suicune, and Raikou) will have a red life bar all the time when encountered.

In this game, using the Pokeball on an enemy with red health guarantees a capture. blue and green bars indicates that they're uncatchable; Pokémon with blue health bars are Boss Pokemon and cannot be captured at all.

To capture a Pokémon, simply drag the large Pokeball from the bottom-right corner of the screen over to the Pokémon. If the Pokémon meets the criteria for capture, the Pokeball will open and will catch the Pokémon upon release. While dragging the Pokeball around the screen, the movements of all Pokémon will pause.