Elex

This achievement is for getting 5 companions through the game. I will list the 7 main companions and where to get them. Also, this obviously has a few spoilers.
Duras- You meet him at the beginning of the game. Do his quest to solve the murder and side with him at the end.
Falk - He can be found at the top of the converter in Edan that the Berserkers shut down. Just talk to him and be nice and he’ll follow you.
Caja- She can be found in the Domed City in Abessa. When you enter the city, go to the right side down into the district with the separatists and you’ll find her.
Ray- He can be found at Sandy Pines at the entrance to the Tavar region. You should have a quest for stolen property at the beginning of the game. Follow the quest to find him.
Nasty- She can be found in the Fort, just before the Duke’s tower, near the missile silo thingy. Talk to her and do her quest to recruit her.
CRONY U4- You can get this little guy pretty easily. At the beginning of the game, inspect the dead robot U3 to get the quest.
Arx - Credit to an annoyance for this one! Arx can be found south of the Domed City in a small building directly south of the squarish looking road intersection. He will join you after a short conversation though he also gives you a quest you can do.
Thanks, this is my first guide, so don’t crucify me. If anyone has anything to add or want to confirm U4, feel free.

Below is a map with the specific locations of each of the companions.
You only need to get each companion to join you for the achievement they each have their own missions but they are not required for the achievement