There are two versions of Mega Man Battle Network 6 - Cybeast Gregar and Cybeast Falzar, both for the GBA.
Falzar, an ancient creature embodying the form of a terrifying bird, has been awakened and unleashed on the Internet. This is the biggest challenge Lan and Mega Man have ever faced. It is now up to you to help them on their journey.
A long time ago, two ancient creatures with unimaginable power ravaged the internet. These two 'Cybeasts' clashed against each other with such force that the virtual landscape change forever. One was a monstrous bird called Falzar and the other - known as Gregar - embodied the form of a vicious wolf with massive fangs. After their last known altercation, all that remained was a huge crater - known as the Underground. The creatures laid there in slumber, until someone woke them and unleashed them on the 'net. Mega Man eventually intervenes and manages to contain one of the 'Cybeasts' within him. Each 'Cybeast' is the final boss gamers must face in the two versions of the game.
There are new features to this chapter in the Mega Man story. There is a new 'Cross System' that lets Mega Man utilise the special power of various allies when in battle. There is also the 'Beast Out System', which allows players the use of various 'Cybeasts' abilities. Gamers can also compare records and have Net battles with friends.