As far as "coverage" is concerned, the best you can do is a Mold Breaker Basculin with Soak, Hidden Power for Electric, Superpower, and Mud Shot. Just the first two moves already cover everything except Arceus and Silvally, and the last two moves make it so that even those two have to be holding the item for one of eight specific types in order to avoid the dreaded "super effective" message.
Then again, the hits this dishes out aren't very strong, other than getting a x2 multiplier that takes two turns to bring to fruition.