WoT explaining the physics behind it(and yes im using all the sources we can and im not discounting anything).
Aiming electricity isnt possible by normal means, the only way to do it, is
A. Having a closed space(not our case)
or
B. Making it follow ions, to be more prescise, ionized gas(plasma).
There are lots of ways to produce plasma, like lightining, fire, etc.... And just so you know, it isnt PLASMA that create those, it is plasma that is a colateral effect(aka plasma is created by those).
So back to the mu: The only way for samus to guide her electricity shots are with plasma, but plasma dosent stay still, it dissipates really fast, and its really hard to control.
The only 2 effective ways to get plasma to guide prescisely elec are:
A. Closed space(not the case).
or
B. Getting the electricity to follow the ionized plasma as soon as it makes the path you want.
So theoretically if samus wanted for elec to score, she would need to be able to create a plasma path reaching his adversary, and making a eletric current go through it immediately after she got that path on.
Then we get to our next problem, how is she going to produce that plasma in a way it dosent dissipate and reaches the target prescisely?
The answers are 2:
Ionizing the target(impossible to this mu).
Or ionizing the path really fast, and the only realisticly ways to do that are with heat followed by electricity, or creating magnetic discharges(making a whole place + or -) which isnt possible either.
So her only option is to produce a very hot "thing"(laser in case) so that it will ionize the gas and make a path for electricity.
But, HERE IS OUR PROBLEM, she dosent have any type of "super hot laser", and she isnt able to shoot both at the same time(only way to make sure gas wont dissipate).
So there we come to a conclusion: She cant aim the electricity, meaning her only weapons are Charge beam and homming missles.
@Mu: This ends up being Charge beam + missles vs (That imba Ak riffle) + Railgun.