Sorry, but there is no way (even if you defeat all the black navi's, the music remains). The only thing you can do is save before the expo and continue through the last dungeon/boss without saving but that's very difficult. It sucks, I know.
attack them from behind.
You dont. It's only for falzar version.
The only way you can get it without cheating is by trading a guy in the game for it
in undernet 2 on the oppsite side of the bbs board you must have baaten falzar/gregar and have 100 chips in your library ... enjoy gameing
http://www.gamefaqs.com/boards/genmessage.php?board=929993&topic=31803681&page=11
Aquarium HP
Cyber Beast Gregar is in the Copybot Comp. The Copybot Comp is the last stage of the game. After you beat all the other bosses in the Pavilion, you have to battle Gregar. Gregar is the final boss.
To jack into a system in "MegaMan Battle Network: Cybeast Gregar" using Visual Boy Advance, first ensure you are in an area where you can access a terminal, such as a computer or a Net Navi. Approach the terminal and press the "A" button to interact with it. Once you confirm your action, MegaMan will be jacked into the Cyberworld, and you can continue your adventure. Make sure your emulator settings are configured correctly for smooth gameplay.
6 versions: MMBN, MMBN2, MMBN3 Blue and White (Japanese Black), MMBN4 Redsun and Bluemoon, MMBN5 Team Colonel and Team Protoman (DoubleTeam for DS), MMBN6 Cybeast Gregar and Cybeast Falzar.
u can find them at this site http://www.gamefaqs.com/boards/genmessage.php?board=929993&topic=31803681&page=11
it's in udernet 2 when you go to the big skull, go left
dont know but megaman battle network 6 cybeast falzar(red bird)/gregar(blue lion) has 5 transformations plus an special transformation (f beast/g beast) that you can fuse with the other 5 meaning 11 transformations in all