If you guys need some clarification on how something works, you can always ask me or anybody else in this thread who is super knowledgable in Digimon.
It's very similar to Pokemon, but your Digimon is made out of data, they are stronger than Pokemon when they reach Champion level or higher, and they can Digivolve back and forth up their preferred Digivolution tree.
Most Digimon's preferred state is their Rookie form (unless you have a Gatomon, as she is a Champion level Digimon and can hold it as if it were a Rookie form), as that uses less amounts of energy to uphold while also giving them adequate amounts of power to protect themselves from threats. With the help of gaining more power or through the help of a human, they can achieve more powerful forms.
When a Digimon is damaged significantly to the point of not holding their stronger form, they'll either transform back to their preferred form or into their In-Training/Fresh level form. If they are beaten severely, they'll turn into an egg and they'll hatch with their memory intact in most cases.
The tree of Level forms goes like this (Westernized wording with Japanese wording in parantheses):
Fresh (Baby I) - In-Training (Baby II) - Rookie (Child) - Champion (Adult) - Ultimate (Perfect) - Mega (Ultimate)
For some god-awful reason, the company in charge of westernizing the Digimon stuff for the North American audiences thought that switching the terms around for the last two (as they mean differently culturally here than it does in Japan) would be a good idea.
Now, it gets confusing when someone says Mega when they mean Ultimate.
