I'd start by completely re-evaluating the Manectric set. It is strictly a special attacker so there is no need to slap on a third stab in Wild Charge on there which will be doing pretty pitiful damage while giving recoil. Also Electro Ball is pretty dog crap. Apologies if this assumption is wrong but I'm guessing you aren't all too invested in competitive batteling (given the set (lack of understanding in moveset/choice scarf)) and it wouldn't be silly of me to assume you won't be utilizing the pros of EVs, Natures and IVs to your advantage so at level 100 we are probably looking at a Manectric with about 250-280 speed. This becomes 375-420(blaze it) when attached with choice scarf.
Given them stats (and ignoring Tailwind, Yanmega is choiced, you don't want to lock it into Tailwind now will you want to lock yourself into Thunder Wave with Manectric. Choice Scarf increases speed to 150% but only allows one choice of move), for Manectric to be dealing max damage with Electro Ball (150 power) the opponent must have a speed of 93.75-105 which is extremely low, most Pokemon have more speed than that by level 50... The kinds of Pokemon that will be slower than that are Pokemon like Ferrothorn and Snorlax that have no problems dealing with it.
To demonstrate, a Manectric of 280 speed and 270 SAtk using Electro Ball against a standard Snorlax of 96 speed (meaning Electro Ball is at 150 power) will be dishing out less than 32% which isn't even a 3HKO. Maybe even a 4HKO with leftovers.
-220 SpA Manectric Electro Ball (150 BP) vs. 144 HP / 176+ SpD Snorlax: 133-157 (26.7 - 31.5%) -- 22.1% chance to 4HKO after Leftovers recovery
That was just max damage. To get 120BP, you need to be above 25% of the user but under 33% which is looking at 125-140 speed which is extremely slow. Most slow Pokemon beat that with no investment.
To get 80BP which is relatively weak, it needs to have more than 140 speed which is extremely likely
To get 60BP, the opposing Pokemon needs to have more than 50% of your speed which is 187-210 speed which is very average speed. 60% of the Pokemon you face will be hit for 60BP :P
Just thought this might change your outlook on Electro Ball.