I love when these guys show up in a discussion. An OP who clearly has never done EV, and is just looking for some friendly advice on gear, and someone always shows up saying 'lol lvl 40 greens is fine.'
I could actually go even beyond that and say that if others in your group have good gear, you can do 4 out of 5 bosses completely naked wearing no gear at all. There are of course some phases where all group members will take damage and if you are completely naked you will probably die, but even that does not matter, since the rest of the group can just do it without you and revive you after.
The fourth boss encounter however you cant do naked, since it requires you to beat one target alone and others are not allowed to help you by more than one hit.