Champion class is the term used which refers to the 4th class of Digimon evolution.
Almost all Digimon reach this class of evolution, which is progressed by the rookie class.
Continuing on to Ultimate class before death from old age is usually a challenge.
Champion class are the most common class encoutered as by enemies.
Their shape and size varies extensively, although the average would problably be about the size of a real-life elephant or dinosaur.