Electro Ball is almost always outclassed, even on faster Pokémon.
While Electrode is one heckuva speedster, and so are other Pokémon like Mega Manectric and Galvantula, they all typically run Thunderbolt, Volt Switch and Thunder, respectively. Why is Elctro Ball near the bottom of the barrel of Electric attacks? It's because it has a fluctuating damage ratio. Here is the formula for Electro Ball's base power:
r = UserSpeed ÷ TargetSpeed
Now, while Electrode is one of the fastest Pokémon, there are other fast Pokémon out there. There are more competitively viable fast Pokémon than competitively viable slow Pokémon. Let's find the base power of Electro Ball versus some of the metagame's speedier 'Mons. (using their max Speed stat, 31 IVs, 252 EVs, positive nature)
Electrode vs. Talonflame
r = 416 ÷ 386 = 1.07720207…
According to the Pokémon DB's page for Electro Ball, the damage ratio for Electrode versus Talonflame is 1≤ r < 2, making Electro Ball's base power 60. That is the same as the Electric Hidden Power. Thunderbolt has a base power of 90, making it the superior option.
Electrode vs. Mega Metagross
r = 416 ÷ 350 = 1.18857…
Damage ratio is 1≤ r < 2, making Electro Ball's base power 60 once again.
Electrode vs. Hydreigon
r = 416 ÷ 324 = 1.28395…
Damage ratio is, again, 1≤ r < 2, and the base power is again 60. This is an important benchmark, though, because Hydreigon, at 98 Speed, underspeeds the crowded 100 speed tier. This means that Electrode won't be able to hit any Pokémon with 100 speed or above, which is a good chunk of the metagame, for more that 60 base power, making Electro Ball inferior to Thunderbolt. This includes Mega Charizard Y, Thundurus, Volcarona, and more.
Electrode vs. Bisharp
r = 416 ÷ 262 = 1.587786:
The ratio is 1≤ r <2 for a base 70 Pokémon. This is starting to get low in the Speed tiers. And granted, while most Bisharp run Adamant over a speed-boosting nature, there are many base 70s that do (Breloom, for example).
TL;DR Electro Ball is almost always inferior to Thunderbolt or Volt Switch unless you specifically want to target really slow Pokémon like Mega Sableye or Mega Slowbro.
EDIT: I just wanted to say this to clear up a possible contradiction to my argument, the move Gyro Ball functions exactly opposite of Electro Ball, running off of how slow you are compared to your opponent. Gyro Ball, while viable only on a few Pokémon like Ferrothorn, is easier to justify using since a) most Pokémon that get it are really slow and b) since the majority of the metagame is really fast, Gyro Ball can benefit from what hinders Electro Ball.