Complete the main Chocobo Forests on Centra and Trabia (3 in each, IIRC). Take a chocobo from the forest nearest Trabia Garden and work your way east until you you're able to get on north-eastern peninsula of the Eastern Continent that's completely covered in forest. The Chocobo Sanctuary is located in the the north end of this forest.
Once you enter, "talk" to the Chocobos, watch their dance, and then try to "talk" to the little Chicobo that's left. You'll receive the Chicobo Card. --- Back from the dead.... or maybe just Tokyo.
You need the JP-only and long since discontinued PocketStation - or a cheat device - to power up the actual Chicobo attack (use Gysahl Greens in battle) or to obtain the items Friendship, Mog's Amulet, Ribbon, and Chocobo's Tag.
But as far as the card and the general chocobo forest sidequest is concerned, you don't need a PocketStation. --- - Vilurum Xaren, leader of the happy turtles, and knowitall. ... And if you can't spell "Vilurum", call me "Vil". :)