Ok so there are achievements for playing most of the game with the same squad members, and I played every mission I could with Garrus and Wrex. Only one mission I didnt chose Wrex (the Noveria one) where I chose Liara instead because Benezia is her mother. But I used Garrus for every mission and Wrex for every mission except Noveria, and I didnt get the achievement for using either of them for a majority of them game. WTF! Is this a bug or something? Or do I have to play through again to get the achievements?

:/ Sorry I have no idea. Just so you know I haven't got that achievement either when I only changed character like once or twice. So maybe you actually need to do every mission with them to get the achievement (stupid, I know).

But then again, if you do side quests, like exploring the planets and collecting resources but take Wrex and Garrus with you again, then you might get the achievement. Don't take my word for it though.

It DOES include side quests. The game will only think you played the majority of the game with a certain squad member if you do praticaly all the side quests.

It sucks to be honest, you got to go throught the game at least three times to get all the squad member achievements.

You have to use those characters for the majority of the game. As far as I know, you can only get two squad achievements per playthrough. Use 2 other characters ONLY until you get the achievement.

Only doing the main missions is not enough for this achievement. Just do a few of the major sidequests and you should get the achievement soon.

you have to do a shit ton of side quests like 40 of them and 4/5 of the story, with the charcters you want to get the achievments for. i have 1000/1000 on this game trust me.