I know 2 ways to rip GBA and GBC sprites
1.
Visual Boy Advance has tools for sprite ripping.
You can find them in
Tools.
You'll need the
Map Viewer, OAM Viewer and
Tile Viewer. What you use depends on what you want to rip.
Now you can save them as pngs and make a sheet in Paint or another program.
2.
I use this technique for animated stuff
For this you use something called frame advance. This means you can play the game frame by frame.
Note: this works with the standart emulator, but its easier if you use an emlulator which supports
rerecording, because the standart emulator doesn't update the screen if you use frame advance.
To get the sprites you just have to make a Screenshot.
You can disable layers, to get most of the sprites on a blank background.
Be carefull if you use screenshots for GBC games, because Visual Boy Advance crops it a bit on the smallest screen setting. To work around this issue, I set the window to two times as lange, so every pixel is 2x2 pixels. Then I take the screenshots and shrink them down in paint.
I'm sure there is a better way, but I don't know.
Anyway, good luck!
Edit: If you want to compress you sheet a bit to make it smaller, then you can use
PngGauntlet. Very usefull and easy tool.