Raichu is not a popular pokemon. Letting aside that it’s not spectacularly powerful or especially unique, being a fast-offense Electric type, one has to also take into account the absurd popularity of Pikachu as a mascot pokemon, particularly when combined with the ability of Light Ball to double the lesser rodent’s special attack power.
Still, the fact of the matter is that while it’s not amazing, Raichu simply isn’t weak, and it deserves more respect than it gets.
While its defenses are nothing to cheer over, Raichu has a decent 100 speed rating and similarly decent 90 attack ratings. I say ratings because its physical attack is the equal of its special attack- and that’s where it can demonstrate an unusual trick.
Being an electric type and having the reputation associated with its evolutionary line, anyone seeing a Raichu pop out of your lineup is liable to jump to two conclusions.
One, this thing isn’t going to be dangerous. Two, you’re going to be wielding special attacks through it.
This gives you an opportunity- perhaps not one that will be repeated, but still it is an opportunity- to surprise your opponent in a few ways.
First off, while its offensive power isn’t startling by any means, Raichu offers you the opportunity to put a few significant holes in your opponent’s team. 100 speed isn’t the best out there, but it’s nothing to sneeze at, and by packing a few strong offensive moves such as Thunderbolt, Grass Knot, Hyper Beam, and Focus Blast, a set that offers some good opportunities to poke holes- particularly with Grass Knot and Focus Blast- in the type of pokemon that typically counters an Electric pokemon.
This on its own isn’t enough to recommend Raichu, though. Even an opponent not anticipating the level of damage Raichu can dish out will likely put out something with good Special Defense that can take a hit and use the opportunity to boost itself with a power-up move.
Where Raichu can really surprise is by packing a truly unusual combination: Brick Break, Giga Impact, and Thunderpunch can give it a good shot at taking out some of the things it would ordinarily be troubled by (Rock types especially), paralyze things that it can take a decent chunk out of with Thunderpunch, and then try and get a second swing in to clobber its foe with Giga Impact.
While it’s unlikely to be a highly-reusable trick, it will help keep your opponent on their toes, and really is a demonstration of a broader principle that Raichu serves as a perfect reminder of:
Just because a pokemon isn’t the best at something doesn’t mean it can’t still do it well, and just because a pokemon has a reputation for something doesn’t mean it can’t be used for anything else. Physical-offense Raichu is only one example, and while it isn’t a perfect one, it stands out especially when you take into account not only its reputation but its relation to Pikachu.