I read a few pages about companions in fallout wiki. Red, Shorty and especially Sticky are very vulnerable w/o any decent armor. So you could imagine that I have to restart old saves if in case they were dead during questing.
I got sticky right after I enter lamplight caverns (you just have to wait a few hours or so in game time). He'll ask you a favor to escort him to big town and for my situation, I don't have to and amazingly he'll use whatever armor and even energy weapons you gave him (he's pretty good at least with a gattling lazer and a gauss rifle <---- great knock back weapon). While Shorty and Red can be found at German town HQ, you'll receive a quest called "big trouble at bigtown" and you don't have to bring all of the 3 "temporary" followers to big town at all

.
The added difficulty with these companions is that for one, they have very low health, secondly they don't automatically heal after battles, they can flee during battles, activating traps and can get hostile easily if fired upon (1-2 shots). Eventually I end with a very versatile team who can pretty much kill anything even a behemoth on very hard difficulty (which I did last night) with the aid of a gauss and victory rifle for knockbacks