There are a few glitches in the Sonic Adventure series relating to the Chao system. Some are useful (some would say essential even!), and some are just quirky.
Infinite Small Animal Use
Probably the most famous glitch in the game, and essential to know for quick, efficient Chao raising. Raising your Chao’s stats normally can be a long and tiring task. It requires you to collect a maximum of 10 Chaos Drives and/or small animals within the levels of the main game, going into Chao World afterwards to give them to your Chao.
Since you can only have 10 Chaos Drives or animals at a time, this becomes very repetitive. I’m sure that with your first few Chao you kept repeating levels over and over again just to raise your Chao’s stats!
Usually when you give a Chao a small animal, the Chao grabs it, embraces it, and then the animal bounces up and away from it becoming un-interactable and disappearing shortly after when off screen. However, instead of letting your Chao grab the small animal off of you - you can trick the game by placing the small animal directly in front of the Chao. When done properly, the Chao will absorb the animal as if you had given it to the Chao directly. The Chao will sparkle as usualy and the animal will again be flung away from the Chao - but it will still be interactble! This means you can grab the animal again and re-use it. When you get the hang of it, you can use the same small animal an endless amount of times and benefit from the stat gains each time.
It is easier to have your Chao stay in one place for this. So it’s a good idea to pet, or pick up and put down your Chao so you can align yourself properly with it.
Infinte Chaos Drive Use
As with the animal glitch above, the same process can be applied to Chaos Drives. Due to the bouncy behaviour of the Chaos Drives and the large space it takes in the characters hands, it can be tricky to perform correctly. It works in exactly the same way as above though.
Dreamcast Health Center Crash
(Sonic Adventure 2 Dreamcast only)
There is a glitch on the Dreamcast version of Sonic Adventure 2 where it was said that if you take your reincarnated Chao to the Chao Doctor - it could crash your game and corrupt your save file!
The reason for this is due to the poor translation from Japanese. When you take your Chao to the Health Center anytime after it reincarnates, you have the chance of being told how many times the Chao has done so.
The thing is, this message is horribly bugged and will crash your game shortly after seeing it, with the risk of corrupting your entire save file!
This doesn’t happen with the Japanese version of the message. When using Japanese text, the message is entirely normal and does not crash your game or run the risk of losing your save file.
Dreamcast Glitch Chao
(Sonic Adventure 2 Dreamcast only)
When Sonic Adventure 2 was first released on the Dreamcast, a lot of peoples first thought was “I wonder if I can transfer my Chao from Sonic Adventure into Sonic Adventure 2 using the VMU??” Well, you could! Except that when the Chao game out it was horribly glitched and appeared as a regular coloured Chao regardless of what you transfered (and seemed to gain the name DUMMY).
It was found out that once the glitch Chao reincarnates, it gains its original colour back (so Jewel or Black colour if you transfered one of those).
Mystic Ruins Garden Suicide
(Sonic Adventure Dreamcast only)
On the Dreamcast you can jump off the side of the garden in the Mystic Ruins and you will lose a life. You can also grab a Chao and jump off too! It will not kill the Chao. Thanks to Torro for testing this as I didn’t want to risk my own Chao.
Black Market Ring Glitch
(Sonic Adventure 2 Gamecube and PC)
Gamecube: In games with the Black Market within Chao World, you can sell an item (usually something worth a lot of rings) and then soft-reset the game right as you hear the ring counter sound. This will result in the new ring count saving, but not saving Chao World - so you get the item back in your garden! Make sure you have saved the game before you do this, or any Chao raising progress will be lost.
PC: After you sell an item, you need to go into the pause menu options and change an option so the game saves the config data. Then you force quit the game.
Gamecube Tiny Chao Garden Transfer Danger
(Sonic Adventure 2 Battle Gamecube only)
On the subject of making sure your Chao World data is saved - the Chao Transporter in Sonic Adventure 2 Battle has an inconsistent saving method which has resulted in many sad Chao raisers.
As explained on the Chao Transporter page, you can transfer Chao and items back and forth between the GameCube and Game Boy Advance games. However, Sonic Adventure 2 Battle fails to save the game after a “Pick up”, and instead only saves after a “Drop off”, “Move”, or “Good-bye”! The Tiny Chao Garden correctly saves in all cases. This can have serious consequences if you aren’t aware of it.
If you transfer anything from your Tiny Chao Garden over to Sonic Adventure 2 Battle, and then turn off your GameCube (or your game freezes), you will have permanently lost everything that you transferred! This is because the Tiny Chao Garden will have correctly saved that it no longer has the Chao or items, but the regular Chao Garden will not have saved that it received the Chao or items. If this happens to you, there is no way to get back what you lost.
To avoid this issue, you should manually save the game right away by exiting the regular Chao Garden in Sonic Adventure 2 Battle immediately after transferring anything over. You only need to do this after a “Pick up”, not after a “Drop off”.
Shiny Jewel Chao (Invisible Chao)
(All modern versions)
Shiny Jewel Chao, as mentioned on the (info-center/advanced/colours)[Colours] page, look different depending on the system you are playing. If you look at Sonic Adventure DX, they also appear differently on the GameCube and PC versions, and not at all on PS3 and Xbox 360. This inconsistent behaviour leads many people to believe that they are glitch. It is possible that they were never intended to be in the game.
Regular Coloured Mono-tone Chao
(All modern versions)
Originally brought to the public eye by Shining Chaos Chao (one of the first Chao Island moderators). All Chao colours have a Monotone and Two-tone version. This includes the Regular coloured Chao! The original default blue/yellow coloured Chao you first get in the Chao Gardens is a Two-tone Regular coloured Chao. So what does the Monotone version of this Chao look like? Well it varies. For the most part, the Chao stays a monotone colour, but the colour depends on the alignment and evolution. For example, Neutral Chao takes on the colour of the dominant colour of the type you would usually find on it (eg a Neutral Fly Chao is all purple), while the Dark Chao seem to take on the colour of the highlight (eg a Dark Power Chao is all orange - the colour of its usuall non monotone highlight). The Hero Chao all appear to come out plain white. The exception to this is the Neutral Swim Chao which seems to have different colours for its feet and tail compared to the rest of its body!
(Sonic Adventure 2 HD Remakes)
Bright Chao are shiny two-tone Chao from the HD remakes of Sonic Adventure 2 for Xbox, Playstation and PC platforms. However, due to a porting glitch, their appearance is very bright - hence the community nickname “Bright Chao”. They still behave genetically as a Shiny Two-tone, such as carrying the Shiny gene. Bright Chao usually appear all white with little to no visible highlights. However, when the Bright Chao is a dark type, you can start to see their colours and only their highlights appear bright.
PC Neutral Garden Fruit texture glitch
(Sonic Adventure 2 Steam)
On the Steam version of Sonic Adventure 2, there is a glitch involving the Chao Stadium Races and the texture of the mating flowers, and the Neutral Garden fruit. It seems to only be triggered by competing in the races - you don’t even have to complete the race (eg, you can just load one and exit). After you exite back into the Chao Garden, you will notice all the Neutral Garden fruit have their texture changed to a dull green, along with mating flowers the wrong texture too.
Simply entering the cave won’t trigger the glitch, Chao Karate does not trigger it, the race menu won’t trigger it. Only actually starting a Race will cause it.
It is reset back to normal after exiting Chao World.
Planted Tree glitch
(Sonic Adventure 2 Steam)
When your Chao plants trees, they will grow in a glitched way where only some of the tree is visible. Only part of the stalk, leaves and the fruit can be seen.
Hero Chao texture glitch (Run and Power types)
(All Sonic Adventure 2 HD Remakes)
(Sonic Adventure DX Steam, Xbox360 and PS3 Remakes)
In the modern releases of SADX and SA2, there is a glitch with the palette file making Run and Power type Hero Chao display incorrectly, as seen in the images below.
Here are the details summarised by LimitCrown:
The Gamecube games and SADX PC 2004 display the colours correctly. In these games, the palette index texture has a 4-bit palette format, so each part of the texture can have a value in the range of 0-15.
The index texture references a palette file to determine the colours each part of the Chao should have. This index texture has a 16-byte header followed by 48 entries of colours in the RGB565 format, each colour being two bytes large.
Every set of 16 colours in a palette file corresponds to a different body texture for a specific Chao form. For Hero Chao, the first set corresponds to the texture used for the head and the limbs, the second set corresponds to the texture used for the body, and the third set corresponds to the texture used for the wings.
For Child Chao, the first set corresponds to the texture used for the tip of the head and the limbs, the second set corresponds to the texture for the spots on the back of the head, and the third corresponds to the texture for the body.
In the modern releases of SADX and SA2, the palette index textures and the colours of the palette file have interpolation applied to both separately instead of being applied to the texture after all of the colours have been assigned.
Sonic Adventure 2 Steam running too fast
Sonic Adventure 2 on Steam is hardcoded to work on 60Hz and has no vsync option. If you have a monitor that has a faster refresh rate than this (eg. 120Hz, 144Hz, etc) you will see the game run at the appropriate frames per second. So if you have a brand new 144Hz silky smooth monitor, you will see the SA2 game run at 144fps where the menu, animations and gameplay will be over twice as fast!!
The easiest way to get around this is to set your monitor to 60Hz in the display options.
However, this isn’t ideal, because then either you miss out on the excellent max refresh rate on your monitor (which you probably paid extra for), or you have to keep changing the refresh rate back and forth every time you play the game.
The other option is if you have an Nvidia graphics card. You can use the Nvidia Control Panel to set the refresh rate per game.
Open up the Nvidia Control Panel and go to Manage 3D Settings. From here, press the Program Settings tab. Select sonic2app.exe from the list. If it is not showing on the list, start up the game and then close it, and it should get added to the top of the list.
Scroll down to Max Frame Rate and set this to 60FPS. Now scroll down to Vertical Sync and set this to Use the 3D application setting. Click Apply!
NOTE: you will need to run the game in full screen for this to work, if you try to play in non-full screen (windowed mode), the game will crash before the intro animation. For windowed mode you will need to manually set your monitor refresh rate to 60Hz as described first.