*A few days later*
I finally was able to beat Pharsis and Telethia with this skell!
Here is my stats when I've beaten Pharsis:
I kind of brute forced my way by equipping the best augments. It ended up not bad stat-wise: capable of dodging most of the attacks, good element resistance (here 110 gravity against Pharsis), good R-attack and 5700GP to be able to enter *almost* infinite overdrive mode.
I didn't want to use diskbomb to avoid introducing a 3rd attack type. instead, the SA B-Rifle (beam) and SA Assault Rifle (physical) + GP gain for arts were enough to build the GP gauge quickly.
I'm happy with the result and seeing that I can do good amount of damage with the beam weapons despite having a mix with physical ones, I think I'll switch to 100% beam because I like how these weapons look and feel.
Anyway, thanks again. Your advise was a great help
Zalusithix!
BTW, just after that I tried my Lailah Queen with a 100% thermal weapons and diskbomb. She obliterated these bosses without blinking and she didn't even have proper augments (except the thermal reflect cancel and a couple of leftovers I had).
It's a shame the skells aren't well balanced at all but I'm happy I was able to make Urban Lincoln capable of doing anything. Granted, his almost perma overdrive helped a lot.
Shion & Weltall