How do you unlock it?

Games Other Halo
1

If it matters wether you beat halo 4 on legendary solo or co-op to unlock mark VI?

2

As long as you complete the Campaign on Legendary, Co-op or Solo, then you get the original Mark VI

3

All it says is beat the campaign on Legendary so I would guess that means, Co-op or Solo, it doesn’t make a difference as long as you beat it on Legendary.

4

As long as you complete the Campaign on Legendary, Co-op or Solo, then you get the original Mark VI