Wouldn't it be nice if you could reuse those ten Chaos Drives over and over again?
Well... you can. It's cheating, or at the least taking advantage of a glitch, but there's no faster way to raise your Chao's stats.
This will require good timing and a bit of practice.
First, go into the garden with some Chaos Drives. Grab your Chao. Stand facing away from the Chaos Drives and set your Chao down.
Pet the Chao.
This will keep her still long enough for you to turn around and pick up a Chaos Drive.
Imagine the width of a Chao, and stand about one and a half to two times that distance away from your Chao, holding the Chaos Drive. It helps to look at the shadows of yourself and the Chao to make sure you're aligned right.
Put the Chaos Drive down.
The game will recognise that you didn't use the Chaos Drive, but the Chao will act as if you gave it the drive anyway! You know you got it right because the Chaos Drive will fly right up over your head to join the others behind you.
Repeat.
This also works with animals, but you need to stand a little bit closer to the Chao. Just keep picking the animal up and putting it down. You can farm your Chao's stats insanely fast with this trick. I advise you not to do too much at one sitting though, as you can bluescreen the Gamecube.