Instructions
Tap the "Attack" option, followed by the attack that you want to use on the oddly colored Pokemon.
Continue to attack the oddly colored Pokemon until its health bar turns red. The goal when catching a Pokemon is to get the Pokemon's hit-points as close to one as possible without killing it.
Tap the "Items" option and select the Poke Ball you want to use. For a better chance at catching the oddly colored Pokemon, use a Great Ball or an Ultra Ball rather than a standard Poke Ball.
Wait until the Poke Ball finishes rocking back and forth. If the Poke Ball rocks back and forth three times and the oddly-colored Pokemon does not escape, you have successfully captured the oddly colored Pokemon.