So, how should I play?

Heya, I'll call myself a newbie, even though I've played a bit in Season 0, and I have a couple of questions about solo Mash, or in general about Mash. The guys I usually play with tell me that it's worth playing either Stellaris or flyers (except Falcon) and bringing energy guns with you. But what if I don't have Stellaris and I don't want to play flyers? I really like Serenit, but they tell me that he really sucks in mash....maybe I would like to play Elisnes, and they tell me that it is not worth playing either.

And what should I do then? Just play on normal difficulty as the mechs I like? I just want to take the rewards from there, and I'm kinda enjoying the mode in general. The pve part atleast for sure.

Even if I'll play just as those I like, what weapons I ideally should bring in as a meele or a ranged mech?