This achievement is based on story and cannot be missed
You get this upon turning the quest to Vaughn

Be very careful with this achievement and patient.
While arming the moonshot, you should proceed slowly and allow Tiny Tina to arm the moonshot
Very easy to miss if you are in a rush
You have to talk to Tina. She will not automatically push the button


What if you missed this achievement?
Sadly, you cannot go back. Therefore, you need to start the DLC again. Some suggestions
-You have to start the the DLC with another character
-You can play the DLC with the same character in another mode like TVHM or normal.
-OR you can reset UVHM with the same character (if that is still possible with the new DLC)
-You can also start a brand new character and just start the dlc

Note: I know the screenshot looks bad and I played the game on my 5-6 year old Acer Laptop

Location map: Dahl Abandon
Who gives the quest? Claptrap Captocurrency
This is a side mission NOT part of the main quest

Special Thanks to z00t for telling me about this achievement

You have to wear the new equipment
You need: 4 weapons, 1 grenade, shield and relic
No class mod needed though

As always, every DLC has a raid boss
Defeat Haderax the invincible

Hint: The new rainbow gear boosts your movement speed which allows you to jump to cliffs on the arena
Note: Hederax will REGENERATE his health so you need to make sure he takes damage everytime he resurfaces.

Thanks to someone in the comments:
get the toothpick set, it's a shield, mod and assault riffle. Also if you slag Hederax it will stop regenerating. Get the overcomponsator as a quest reward.