Electro ball ranges from 60-150 base attack depending on your speed comparison, 50% your total speed or greater is 60, 25% or less is 150, so it can be good, and Paralysis does lower the speed by 50% starting in gen 7, prior to that its reduced by 75%. Agility on pikachu with static would be better than nuzzle imo, since you can double your speed and if you get hit you may paralyze the attacker, basically a guarantee of electro ball hitting for over 100 base, however you need to ask yourself if pikachu can survive a hit before you even get off an electro ball.