Raichu

Raichu's Speed, along with Rain Dance, lets it become a very good middle-to-late-game threat, where incurring 60-70% with a Surf looks a lot better than it did when everything was at full health. A Grass-type works excellently alongside Raichu to help buffer Earthquake, along with the fact that Fire-types won't be at full strength if you use Rain Dance. While once BL in tiers, it has sunk more towards UU as time progressed due to the strengthening of teams and Raichu not matching up well to the new standards: there was a time where Miltank was more popular than Blissey; that was Raichu's prime in GSC. Raichu is simply too fragile to be considered for today's OU play. At the same time, however, it isn't quite the run of the mill useless Pokemon. It isn't very difficult to use, and since it is valuable early in the game to paralyze, in the middle to inflict doses of damage as well as setting up Rain Dance, and late-game to sweep away entire teams of crippled and paralyzed Pokemon. It is a viable, although often neglected, Pokemon.