How do you get the tails chao in sonic adventure battle 2

There is no way to obtain normally a Tails Chao. You need to have the game Phantasy Star online and complete a special quest. Afterward, go to the guild and there should be a transporter, like in the Chao gardens. Go on the transporter and download data on your VMU. Then, open your Sonic Adventure 2 and go to any garden, the Chao transporter chooses the VMU which contains the Chao and now you have a Tails Chao.