Change Enemies In Cyberworld
Get a MegaMan Battle Network 4 Red Sun or Blue Moon. You will need two GBA/SP, and a GBA link cable. Go to Ciel's room in the place you go to after killing Omega. Press up in front of the computer then go to Transmission and In Red Sun/Blue Moon, go to Comm. Then you have to go to trade chips, and trade any chip into Zero 3. In Red Sun/Blue Moon, you will get a secret chip. In Zero 3, all Cyberworld enemies will be changed.
On the second to last level, go into the first hyperspace portal and while you are riding the platforms, you should find a door. This door leads you to 2 disks and a portal. When you go into the portal, you will fight phantom from Megaman Zero 1.