I've only really seen SRM or LRM Stalkers. There was only one x4 PPC Stalker all night. I called him out to my friends and we focused him down. Then again they were trying to brawl with the build or were caught when our line moved up.
Distance and speed are how you kill the Stalker. The Atlas can slug it out but when using my Awesome I lay down the PPC fire from 1000 - 300m. Light faster mechs distract and back stab Stalkers. The LRM travel time, cover, and AMS hamper the long range variants. Just stay far away from the face SRM hugger ones.
On Caustic, I've killed plenty of overheated Stalkers using the PPCs. The same can be said of other snipers.
Edit: One last thing, I had a friend last night running a 4 LL, 2 ML Stalker 5S. It wasn't an alpha damage machine but what I remember from all of our matches is unending laser fire in my ears.
I just built my own 5S with 4 LL, 2 ML, 2 AMS, and 22 DHS. I'll try it out later.
Edited by LaserAngel, 19 December 2012 - 08:55 AM.