Welcome to proving every viable Spark Shock Situation.

Learned things: 
-Spark Shock is a field that stays in place, if one enemy walks in the other walks out

-If an enemy can be killed in 1 pellet, yet also frozen, that is not useful, buster beats it out.
Spark Shock can open the "?" Tanks.


IMMUNE TO SPARK SHOCK:
Metall DX + Flying Variant.
Cannon
Hammer Joe
NEEDLE MAN
Tama: Can't freeze yarn either, fleas are also immune.
Pickelman Bull
PROTO MAN
Magfly
*Giant Springer: Only it's missiles can be frozen.
Bomber Pepe
NAMELESS EGGS IN GEMINI.
Penpen
Penpen Maker
Gyoraibo: Missiles immune also.
Wanaan
HARD MAN: Knuckles go right through it too.
Petit Snakey
Big Snakey
Elec'n
Junk Block (Spark Man Gimmick)
Giant Metall
Hologran
DOC FLASH
BREAK MAN
YELLOW DEVIL MK. II
HOLOGRAPH MEGA MEN
WILY MACHINE 3 PHASE 2
GAMMA PHASE 1
GAMMA PHASE 2


NOT IMMUNE TO SPARK SHOCK:
Yambow: They take 3 bullets.

Hari Harry: can't jump over them.

*Bikky: Can freeze it in air. However, Hard Knuckle kills it in one hit.

Bolton & Nutton: they take 1 pellet, it's better just to shoot them and get them out of the way.

Mechakkero: 1 bullet again

Komasaburo: Always placed in a place to never pass it after freezing it.

TOP MAN: 1 damage. Buster alone does 2 to him so why bother? + Weakness exists.

*New Shotman: Can only be used on very few that can already be avoided.(i.e. Shadow Man beginning)

Peterchy: Always placed in a situation you can't get around if frozen a majority of time,
able to push eachother if one is frozen however.

Walking Bomb: They actually die to it, but they only take 1 bullet, so it doesnt matter.

Parasyu: They are still going to be in your way by the time you're able to freeze it.

SHADOW MAN: Takes 1 damage, same as buster, no point.

*MAGNET MAN: Weakness, need I say more?

Nitron: you can just use shadow blade, they still get in your way when frozen.

Pole: Why would you ever wanna freeze this? 
Once the egg is hatched, freezing it just puts it in the way

GEMINI MAN: 1 damage, again no point.

Chibees: Why would you do that?

Returning Monking: You can just use Shadow Blade and be 10x safer, same with Magnet Missile

Dada: Single Pellet Rule (SPR)

Potton: Can freeze both the enemy and the carrier, but SPR.

Bubukan: Can only be frozen after letting go of the pole. 
Both can be frozen but if Bubukan is holding the pole, it is immune.

Jamacy: Half of the time they're on a ladder and need to be killed, no point.

Bomb Flier: First shot gets rid of the cloud. The 2nd shot actually freezes the bullet.
But this falls under "enemy still in the way."

SNAKE MAN: 1 damage. Zzz. Search Snakes are immune to it.

SPARK MAN: 4 damage, Shadow Bade does more.

DOC METAL: 2nd weakness, Magnet Missile does more damage.

DOC QUICK: Unfortunately, not another thing to call Quick Man weak over. 1 damage.

*DOC AIR: Weakness. Alternatively, Magnet Missile does the same damage (4).

DOC CRASH: 1 damage. Buster does 2.

DOC WOOD: 1 damage.

DOC HEAT: 1 damage.

*DOC BUBBLE: Weakness. Shadow Blade however can be aimed for the same damage.

KAMEGORO MAKER: You can freeze the turtles both in and out of shell.
This of course will deal no damage since you can't destroy the turtles.
The shell alone will be blown up if hit by Spark Shock. 

Have "Su" Bee: Good news, you can freeze them.
Bad News. You'll never be able to freeze them unless you go out of your way by
walking back in Wily 3 to hit a singular one.

Junk Golem: You can freeze them, but why would you do that? They're still in the way.

Junk Block (Junk Golem Attack): For some odd reason, this old gimmick can now be frozen.

*WILY MACHINE 3 PHASE 1: Weakness, this is the one time, it out does another weakness.
Since the boss has no I-frames, you can spam Spark Shock Faster than Knuckle and kill it.


We have concluded. It's outclassed by everything except for boss weaknesses. 
Boss weaknesses however, don't affect the weapon usability much so for actual stages and enemies,
it sucks.