I'm actually a fan of Pikachu (shocking!!). It gets a bad rep for no real reason, its actually a really cute and potent sweeper, when used right of course.
When I ladder, a well played Pikachu is actually something that can sweep my quite often. Lightningrod is an absolutely amazing ability in NU. Seriously. Electric-type attacks are being thrown around left and right from common Scarfers like Rotom-S, Ebuzz, even Zebstrika. Catching one on a Volt Switch and firing off your own Thunderbolts isnt that hard. Though Pikachu is so frail that even resisted coverage moves can 2HKO, so you have to be careful. That being sad, even the threat of Pikachu is enough to make Volt Switch a risky move. If they hit you with it, you now have a +1 Pikachu with a free turn to do whatever you want. Very dangerous, a situation no battler wants to be up against.
The Pikachu I find most threatening is Sub / Tbolt / HP Ice / Encore. It has pretty amazing coverage there, realistically only Piloswine and champion Chinchou dont feel threatened at all, no other resists want to take a thunderbolt. You'll rarely get more than one chance to sweep with Pikachu in a match, so you really have to make the best of it. Even if you cant switch in, Pika isn't slow, it can revenge kill something, base 90 (iirc) is actually quite good in this metagame. Just revenge kill a Braviary!!! :>
also its just so cute, how can you not love it??