I believe energy is based on the mech's size and not their role.  Stalker is considered a medium sized mech and as such has 24 enrgy.

there is no size based classification

Stalker should be 32 energy.

I could be remembering wrong, but originally I think there was.  Stalker being an older mech, I think it fell under that classification.  

Either way though, if you look at the other mech roles, only tanks are always 24 energy.

ohhhh then brickhouse is very big in size he has very less energy like stakler ._. what i say! nonsense ??

LOL  Fair point!!!

Brickhouse used to be a tank, so maybe it did have more to do with roles.  But then again, only tanks are (or have been) consistent with the amout of energy available in each mech.

Stalker is a nasty mech as it is, I personally don't think it needs an adjustment.  That's just my opinion though.

Enegy is based on role but stalker is an exception. With 32 energy this mech would be ridiculously over powered.

Stalker should NOT be 32 energy. Making it that way and having the same ability would throw the balance way off. Even though it's a shell of its former self (very vulnerable  with drive active), the active predator drive is still super deadly. Being 32 energy would effectively make it a 48 energy mech with ability active, versus its current 36. This doesn't even include the Stalker predator drive implant (maximum 30%).

with 24 energy and the 80% more damage (implant included ofc) stalker's energy goes to 43.

with 32 energy just the 50% will make it 48 energy (double the damage one 24 mech can do).

with the 80% buff it becomes like 57.6 energy. thats way too much. it will be able to deal like 474k damage. thats enough to one-shot (both weapons at same time, em-16) a maxed bastion without shield (pilots and all)