Can someone please clear this up for me?

In order to get the Mark VI armor do I need to beat legendary solo or can it be done in co-op? I personally am going at it solo but I have friends who are tackling it co-op and say they will still get the armor. Also has anyone done it offline and still gotten the armor?

Please and thank you!

Both. It can even be done with some in solo and some co-op.

Can be done either.
Everyone will get it.

However, sometimes people are beating the game and not getting the armor.

This is usually due to a glitch or disconnection.

Make sure that you get the commendation for beating a level on legendary, after you complete it.

Start at prologue.

In that case, it should work.

Awesome, Thanks for the quick responses!

I got it in Co-Op.