I just bred a Motor Drive Emolga and I was thinking if it has a Speed boosting ability, nature, its trained in Speed EVs and has the move Agility, will Electro ball be more powerful or does it have to do only with its base stat?
Yes, here is the calculation for an Unboosted Electro Ball 252+ SpA Raichu Electro Ball (80 BP) vs. 4 HP / 252 SpD Blissey: 72-85 (11 - 13%) -- possibly the worst move ever
Here is one for a +6 Speed from the same Pokemon 252+ SpA Raichu Electro Ball (150 BP) vs. 4 HP / 252 SpD Blissey: 135-159 (20.7 - 24.3%) -- possible 6HKO after Leftovers recovery
Source: http://pokemonshowdown.com/damagecalc/
Hope I helped :)