Mega Man ZX

There are two ways to unlock Model Ox, and it can be done on both Normal and Hard Modes (Model Ox is only unavailable on Easy).

One way is to beat Omega, and getting to him involves crossing a spiked pit with disappearing/reappearing blocks. No need to bother with the MMZ3 & 4 game packs with this method.
The other way uses the MMZ3 & 4 game packs; you'll have to beat 4 of the main bosses that are brought in from their respective game pack.

But you still need to finish the game, and save a clear file, before you can activate Model Ox on that file.

Is basically simple, you can get Model Ox by beating Omega at Area N-1, after beating him you return to the area withb a lot of fire monsters and drop to the bottom go right past the doors of MMZ3 and 4, and keep going right if you beat Omega in this area you'll see a rock (Mysterious Rock, name of the item) floating after you grab it go to Guardian HQ an talk to Fleauve select the option 'Talk' he'll tell you that the rock you collected from Area N-1 is really a Biometal and will give you model OX, I really don't know if Model Ox is available in Easy mode, I thinks it is I'm not sure, but beating the MMZ3 or 4 bosses in not required to get Model OX.

-Hope this helped!=-)

You kill Omega in N-1. then, in the room next to the port doors, is an empty room. it won't be empty. the shiny thing in the center? grab it. then beat the game. After you clear the game, go back to Fleuve. Talk to him, and he will make Model OX. Hope it helps at all.