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.
Black Market Ring Glitch
Welcome to Black Market Ring Glitch.
Dreamcast Health Center Crash
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.