Chao evolve to different styles and types of Chao. Chao evolve twice in their lifespan, and it usually takes place over time. Different factors make up the evolution of your Chao, such as what you gave to it and the character you used to care for it.
First Evolution Edit
Once a Chao is born, it will immediately begin the slow process of gradual and first evolution. First evolution is based on what the Chao's alignment is and what Chaos Drives/Animals were used on the Chao. There is a total of 15 possible evolutions. Normal, Swim, Fly, Power, and Run, each of those for each alignment. For example, if you took a baby Chao, cared for it with a mix between hero and dark characters, and gave it 20 Fly Drives, it will become a Neutral/Fly Chao. First evolution takes around 3 hours to complete, and ends when the Chao forms a cocoon to evolve. Additionally, you can feed the Chao fruit to speed up the process.
After a Chao has gone through it's first evolution, it will slowly start to go through second evolution in a similar manner. Second evolution is completely gradual, meaning the Chao doesn't go into a cocoon for this evolution, and it slowly takes place over time. Like first evolution, the Chao changes appearance based on the Chaos Drives/Animals you give to it, however, there's a total of 9 possible outcomes. Normal, Swim, Fly, Run, Power, Swim+Run, Swim+Power, Fly+Run, and Fly+Power. For example, if you gave a Hero/Fly Chao 40 Fly Drives and 40 Run Drives, it will become a Hero/Fly/Fly+Run. Second evolution can take around 10 hours to complete.
Chaos Chao are chao that will never die or grow old. There are three types: Angel (Hero), Light (Neutral), and Devil (Dark). If you follow these steps carefully you will be able to make the chaos chao of your choice. It is recommended that you read this whole section before you begin the process.
The first thing you need to do is have your chao reincarnate two times or more. Reincarnation is when an Adult Chao goes in it's cocoon and comes out as a baby (The cocoon must be pink for reincarnation). To find out, go to the chao doctor, the amount of reincarnations is under "Transformations". It is useful the fact that you can have as many as you want, because it means that you can get an all S chao (if you don't know what this is, then do some research in chao abilities!) Remember, you can't reincarnate the chao ever again, and so you won't be able to raise the Chao's ability ratings!
Once It becomes a child for the third time (remember it starts as a child) the process can begin. Once you have your chao in the right garden, the next step is to give your chao one of every animal. There are 21 animals total, and since you can only carry ten with you, its best to take note of which animals you've gobble gobble gobble your chao, and which you haven't. After your chao has received all 21 animals, the next step is to convert your Chao to the alingment you want it to have.
Most people say that you may not give ANY chaos drives to your chao. However, they are wrong. This has been tested and proved that giving your chao chaos drives will not affect your chao in anyway, shape or form. Please note that you must give them in a balanced order, to keep them a Normal Type.
Once you have completed all of these steps you basically have to play the waiting game. That is you've done everything you need, now you have to wait until your chao gets old enough to evolve for the last time. Once your chao cocoons, you will hear a very distinctive jingle, and you will have your chaos chao. Chaos Chao can still participate in all chao activities except for mating. Since they are immortal, they have no need for reproduction and cannot breed.
If you abuse your chao before it evolves, it will not be a chaos chao.