Greymon

Greymon is a Champion Level Dinosaur Digimon. He is the Digivolved form of Agumon, Tai's companion, in the animated TV series. He is a large, dinosaur-like creature whose skin on his head became hardened and covered with a helmet-like shell. He is a fierce and very aggressive monster. But he is very intelligent and is one of the most powerful champion Digimon.

Digivolution
Greymon's normal digivolution line, as seen in Digimon Adventure and Digimon Adventure 02, goes:
 * Fresh - Botamon
 * In-Training - Koromon
 * Rookie - Agumon
 * Champion - Greymon
 * Ultimate - MetalGreymon
 * Mega - WarGreymon
 * Mega - Omnimon (Dy DNA-digivolution with MetalGarurumon)

When Tai forced Greymon to evolve under dark emotions, he digivolved to SkullGreymon instead. In addition, Agumon also has the ability (at least for the second half part of the first season and parts of the second) to evolve directly from his rookie to his mega form.

Attacks
He has sharp claws and giant horns making his whole body a weapon.
 * Nova Blast/Nova Flame (Mega Flame)
 * Great Horns Attack (Great Antler)
 * Tail Crash
 * Horn Impulse
 * Grey Tooth
 * Fire Wall

Digimon Adventure (The Movie)
In Digimon Adventure (The Movie), Agumon Digivolved to Greymon to fight Parrotmon.

Digimon Adventure
In Digimon Adventure, Tai's Agumon Digivolved to Greymon for the first time to fight Shellmon. After that, he helped to fight against Devimon, Etemon, Tyrannomon, Myotismon, Puppetmon and Machinedramon. During the battle against Etemon, a wild Greymon fought Tai's Greymon until it Digivolved into SkullGreymon and eliminated Etemon's Greymon.

Digimon Adventure: Our War Game
In Our War Game, Agumon became Greymon to fight Infermon, who had just Digivolved from Keramon. Infermon prevented him from Digivolving to MetalGreymon.

Digimon Adventure 02
In Digimon Adventure 02, after the plot to destroy the Digimon Emperor's Control Spires started, Greymon reappeared and took down some of them. The Digimon Emperor took control of him with a Dark Ring and tried to get him to Digivolve to MetalGreymon but instead he became SkullGreymon. Later on, Greymon helped out when Digimon started to appear in the Real World.

V-Tamer
In the V-Tamer manga series, A Greymon worked in Hospitown with 2 Centarumon and a Meramon. They helped to take down Tuskmon when he and Cyclonemon raided Hospitown. Outside of that, a Greymon was an old partner to Neo Saiba who threw him away and became MetalGreymon.