Pet your Chao, evenly, with characters from the Dark and Hero storyline. When your Chao is close to evolving, it should be blue. If your Chao is not blue, but white, pet it with Dark characters, until it becomes blue. If you Chao is black, then pet it with Hero characters, until it turns blue. This does not work after evolution. If using a special Chao (Advanced, Colored, etc.) your Chao's color may not be black, blue, or white.

Pet your Chao with either Sonic, Tails, or Knuckles, excessively. When your Chao is close to evolving, it should be white. If your Chao is not white, pet it with Sonic, Tails, or Knuckles, until it is. This does not work after evolution. If using a special Chao (Advanced, Colored, etc.) your Chao's color may not be white.

Pet your Chao with either Shadow, Eggman, or Rouge, excessively. When your Chao is close to evolving, it should be black. If your Chao is not black, continue petting it with Shadow, Rouge, or Eggman, until it is. This does not work after evolution. If using a special Chao (Advanced, Colored, etc.) your Chao's color may be something other than black.

To make your Chao a Ghost, give it many Bats. Its legs will disappear and it will float.
To make your Chao wear something on its head (other than fruit), give it many Skeleton Dogs. Afterward, give your Chao certain items, and it will do the rest. To set your Chao's floating ball aflame, give it many Half-Fishes. Its floating ball will turn into a blue flame.

Raise a Chao either Dark, Hero, or Neutral alliance. Before evolution, raise that Chao in only one attribute (Swimming, Flying, Running, or Power), so that that one attribute is much higher than the others - recommended that attribute is on level ten, while the others are from one to five. When it evolves, it will be an "Advanced" Chao! The name of your Advanced Chao is formated as follows:
[Alliance] [Attribute] Chao
Examples: Dark Flying Chao, Hero Power Chao, or Neutral Running Chao

Raise an Advanced Chao, then continue raising it in one attribute, while barely raising the other attributes. Try not to raise the other stats past level seven. Your Chao won't evolve, again, but will just change appearance. The name of your Advanced+ Chao is formatted as follows:
[Alliance] [Pre-Evolution Attribute]+[Post-Evolution Attribute]
Chao Examples: Dark Flying+Power Chao, Hero Power+Swimming Chao, or Neutral Running+Running Chao

After your Chao has reincarnated for it's second time, give it one of every animal. It is highly recommended to choose a specific alliance (Dark = "Ultimate Devil" Chao, Hero = "Ultimate Hero", or Neutral), because the appearance of the Chaos Chao dramatically differ.

After a Chao's first reincarnation, give it a Skeleton Dog and an egg shell of the color you want the full egg to be. On it's second reincarnation, it will be a Full Egg Chao!

Raise a Transparent Chao and buy/raise/breed whatever color of Chao you want the Translucent Chao to be*. Once both Chao have evolved, give them a Heart Fruit and breed to get an Egg. When it hatches, it will be a Translucent Chao!
* You can have Advanced Translucent Chao, New Species Translucent Chao, etc.

Buy a Jewel Egg (anything but Gold or Silver) from the Chao Store on Sonic Advance. Buy a Shiny Lime Green Egg from the Black Market on Sonic Adventure 2: Battle. Once they have both evolved, give them both a Heart Fruit and breed to get an Egg. When it hatches, it will be a Transparent Chao!

(Legacy; only obtainable on the Nintendo GameCube)
This trick requires a Game Boy Advance, Sonic Advance, and a link cable. Once you acquire 14,000 rings on Sonic Advance, buy an Aquamarine Egg. Transfer it to Sonic Adventure 2: Battle. Raise it to be a Neutral Chaos Chao (see "Chaos Chao").
This Chao's technical name is "Neutral Aquamarine Chaos Chao."

Hatch a Normal Egg from any Garden. Raise the Chao neutrally. Raise the Chao Advanced (see "Advanced Chao") in Running. When the Chao evolves, it will look like a Green Sonic!
This Chao's technical name is "Neutral Running Chao."

Hatch a Normal Egg from any Garden. Raise the Chao with mainly Dark characters. Raise the Chao Advanced (see "Advanced Chao") in Flying. When the Chao evolves, you'll have a NiGHTs looking Chao. To make your Chao look more like NiGHTs, by giving him longer golden wings, raise it as a Flying+Flying Chao (see "Advanced+ Chao"). This Chao's technical name is "Dark Flying Chao," or "Dark Flying+Flying Chao."

Hatch a Normal Egg from any Garden. Raise the Chao with mainly Dark characters. Raise the Chao Advanced (see "Advanced Chao") in Running. When the Chao evolves, raise it with more running stats until the stripes on its head turn red. Thus, you get a Shadow Chao!
This Chao's technical name is "Dark Running Chao."

Hatch a Normal Egg from any Garden. Raise the Chao neutrally. Raise the Chao Advanced (see "Advanced Chao") in Running. When the Chao evolves, raise it with more running stats until it turns blue. Thus, you get a Sonic Chao!
This Chao's technical name is "Neutral Running+Running Chao."

Buy a Shiny White Egg from the Black Market. Raise the Shiny White Chao with mainly Dark characters. Raise it Advanced (see "Advanced Chao") in Running. When it evolves, it will be a Super Shadow Chao!
This Chao's technical name is "Shiny White Dark Running Chao."

Buy a Shiny Yellow Egg from the Black Market. Raise the Shiny Yellow Chao neutrally. Raise it Advanced (see "Advanced Chao") in Running. When it evolves, it will be a Super Sonic Chao!
This Chao's technical name is "Shiny Yellow Neutral Running Chao."

(Legacy; only obtainable on the Nintendo GameCube)
This trick requires a link cable, Game Boy Advance, Sonic Advance, and a memory card with a saved game from Phantasy Star Online Episode 1 And 2. Play Phantasy Star Online Episode 1 And 2, go to the Hunter's Guild, select the mission "Fake In Yellow." Find the Rappy that used to be a human, talk to it, and it will make a Telepipe. Enter the Telepipe, and you will go to the city. Re-enter the Telepipe. You will see three Rappys staring at something. Talk to all three of them and walk over to place they where staring at. A Chao will appear. It will talk to you and then give you the Key item called "Chao Key." Leave Regol, and in the city, by the Hunters guild, you will see a GameBoy Advance machine like the one in the Chao Garden. Step on it and transport the data to the Game Boy Advance. A Chao will appear in the Game Boy Advance's Tiny Chao Garden. The Chao's name will be Tails. Transport the Chao to the Sonic Adventure 2: Battle Chao Garden. You will now have a Tails Chao!

Note: New Species of Chao can be evolved into any type of Chao given in the list above, excluding the Tails Chao.

Buy a Black Egg or Shiny Black Egg from the Black Market. When possible, breed the Black Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Black with Brown tips!

Buy a Blue Egg or Shiny Blue Egg from the Black Market. When possible, breed the Blue Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Blue with Black tips!

Buy a Pink Egg or Shiny Pink Egg from the Black Market. When possible, breed the Pink Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Blue with Red tips!

Buy a Brown Egg or Shiny Brown Egg from the Black Market. When possible, breed the Brown Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Gold with Brown tips!

Buy a Gray Egg or Shiny Gray Egg from the Black Market. When possible, breed the Gray Chao with a Normal Chao to get an egg. When the egg hatches, if the hatched Chao looks like a Normal Chao, when it gets closer to evolution, it will change colors to be Gray and Yellow!

Buy a Green Egg or Shiny Green Egg from the Black Market. When possible, breed the Green Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Green with Yellow tips!

Buy a Lime Green Egg or Shiny Lime Green Egg from the Black Market. When possible, breed the Lime Green Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Lime Green with Yellow tips!

Buy a Purple Egg or Shiny Purple Egg from the Black Market. When possible, breed the Purple Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Purple with Red tips!

Buy a Red Egg or Shiny Red Egg from the Black Market. When possible, breed the Red Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Red with slightly darker Red tips!

Buy a Sky Blue Egg or Shiny Sky Blue Egg from the Black Market. When possible, breed the Sky Blue Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Sky Blue with Green tips!

Buy a White Egg or Shiny White Egg from the Black Market. When possible, breed the White Chao with a Normal Chao to get an egg. When the egg hatches, if the hatched Chao looks like a Normal Chao, when it gets closer to evolution, it will change colors to be White and Yellow!

Buy a Yellow Egg or Yellow Blue Egg from the Black Market. When possible, breed the Yellow Chao with a Normal Chao to get an egg. When the egg hatches, the hatched Chao should be Yellow with Purple tips!

(Difficult)
When your Chao starts to evolve, run out of the garden, switch characters, and return to Chao World. Enter the garden that has your evolving Chao, wait a few seconds (but not enough for it to evolve) and run out of the garden. Do this many times. Re-enter the garden after the many re-entrances and run into your Chao at full speed, before it evolves. If it works, the cacoon will "burst" (not fade, but sort of sink into the ground at a very fast speed), and your Chao will start crying. If it didn't work, leave and try again, until it works. Your Chao will look exactly the same (yellow on top, not green, like a neutral, evolved Chao would). If you pet him, he won't change alliance, as if he's evolved. Your Chao will never die.
Warning: If every Chao in your gardens die, this Chao will remain. Thusly, you will not get any more eggs (which you would normally get when all Chao die). Because of this, you will be stuck with only one Chao.