I'm not one to cry buff or nerf as I appreciate certain imbalances in warfare that require one to use strategy and tactics to overcome deficits and doing so, contributes largely to my enjoyment of this game.
EMS? - Direct fire weapons and focus fire... LRM spamming? - Use terrain and obstacles to avoid and close to defeat them... Splats? - Keep my distance and pick'm with ranged weapons... Poptards? - Use terrain and obstacles for cover and either counter-snipe or ambush... Boats / high alpha? - Keep moving and accost them when they over-heat...
Light Mechs? (Especially 2 or more working on concert)... I got nothing. I have literally no fear of anything Medium and above but those damn lights... I cringe when I run into them.
I cannot enumerate the number of times I find myself flailing about wildly trying to defend myself from a pair of lights as they spin me in circles and chew me to the bone... It's almost embarrassing.

So... You elite players (You guys know who you are) What are your secrets to handling getting gang-banged by ankle-biters?