Caring for Chao
To make your Chao like you and adore you, you should be nice to them! Hug them and feed them fruit to show your affection. Remember to feed them regularly! To do this, go up to a tree and grab it by holding the action button, then move the analogue stick around to shake the tree. Once some fruit falls down, you can pick it up with the action button and give it to your Chao to make it start eating it. More information is on the fruit page.
Note: While you may typically use the B button as your action button, you can also use the Y button. While in the Chao Garden a good tip is to use the Y button while trying to interact with the Chao to avoid accidentally attacking your Chao with the B button! (B is used for jump attacks and spin dashes)
Happiness is a hidden number which ranges from 0 to 100. There are two known ways to increase a Chao's happiness: picking it up, and feeding it.
It is possible to abuse your Chao, which will obviously make it very upset and traumatised. If you throw or attack your Chao its happiness will decrease. Anything that counts as an attack will harm your Chao - jumping, Amy's hammer, invincibility, etc. and will decrease happiness by 30. It is recommended that you do not abuse your Chao, as repeated attacks can result in immediate death.
If you treat your Chao very well, then it will reincarnate when it dies. For more information, see the Death and Reincarnation section.
Chao react to the different characters that you use to interact with them. For example, if you always look after the Chao with Tails, and you treat it well, then it will begin to like Tails more than the other characters. It will also draw its favourite character as an animal action after giving the Chao a Skunk. On the other hand, if you are very mean to a Chao (either on purpose or by accident), then it will start to despise the character that you used.