All you have to is get your digimon to level 5.(Your digimoncan digivolve to 3 different champions!)
How to get growlmon:
First get a guilmon and train him to level 5 and it will say growlmon.
When you look for the Yellow Cruiser, go to the Asuka Inn and go down a ladder on the left side of the screen. Go through
tht bottom door and take a left through the Under Ground Passage. When you leave the Under Ground Passage, there will be two
stops, one with a blue top and one with a yellow top. Go to the store with the yellow top and, you're there!
In Digimon World 3,digimon must learn digivolves by advancing level.Here are preview digivolves: