Near the end where you see Charmeleon around the lava pool, look to the right. You will see three little lava pools. Toss Pester Balls into all three of them and you can get a picture of arcanine. You can get Arcanine to come out of the first two lava pits or the last one. Try to get a picture of Arcanine when it's shaking embers of its body. You get extra points for this.