Mega Digimon

In the Digimon universe, Mega (called Ultimate in the original Japanese) is the highest known level of digivolution so far. The Mega level follows the Ultimate level of digivolution. In each season of Digimon Anime, only a small number of the protagonist digimon achieves this level. Because of the power of a Mega digimon, this stage is very difficult to reach.

Alternate Mega Levels
Some Mega Digimon are far more powerful than others, many of these having digivolved from other Mega Digimon. One example of this is the Digimon Omnimon which is made up of two other Mega Digimon (WarGreymon and MetalGarurumon) and is more powerful than either of the two component Digimon (he is as strong as WarGreymon and MetalGarurumon put together). In spite of this, such Digimon are still considered to be Mega level although some fans have speculated as to the existence of a level above Mega that contains Digimon such as Omnimon. There is no official support for this theory, but this level is called hyper.

Season One
In the first season, only two of the DigiDestined group's digimon reached the Mega level. This was done through Warp Digivolution. In this process, Agumon and Gabumon digivolved directly from Rookie to Mega level (bypassing both the Champion and Ultimate levels.) Also, several Mega digimon appeared as opponents of the DigiDestined. The Dark Masters
 * WarGreymon (Mega form of Agumon)
 * MetalGarurumon (Mega form of Gabumon)
 * VenomMyotismon (Mega form of Myotismon)
 * MetalEtemon (Mega form of Etemon

The Dark Masters are a group of four Mega Digimon who conquered the Digital World. They never appear outside of their Mega forms, exept sometimes the Digidestined encounter separate Digimon that are their other stages.
 * MetalSeadramon
 * Puppetmon
 * Machinedramon
 * Piedmon

Season Two
In Season Two, only one of the DigiDestined group's Digimon reached the Mega Level. This was done through Mega Digivolution after absorbing one of the Digicores of Azulongmon. This Digimon later changed into a second, more powerful "mode" of its mega form. Also, several Mega Digimon appeared as opponents of the DigiDestined. BlackWarGreymon MaloMyotismon (alternate Mega form of Myotismon)
 * Imperialdramon (Mega form of Paildramon DNA Ultimate form of ExVeemon and Stingmon
 * Imperialdramon Fighter Mode (Mode changed from Imperialdramon)

Season Three
In breaking with the pattern of previous seasons, all of the main DigiDestined group's Digimon reached the Mega Level. These forms were reached via Biomerge Digivolution, in which the Digimon fused with their tamers to reach the Mega Level.
 * Gallantmon (biomerged from Guilmon and Takato)
 * MegaGargomon (biomerged from Terriermon and Henry)
 * Sakuyamon (biomerged from Renamon and Rika)