For as many amazing and devastating Pokemon there are in the Johto region, there are just as many Pokemon that any self-respecting player would be better off passing over.
While a Pokemon being underwhelming doesn't necessarily mean that it is terrible, a Pokemon is certainly bad if it's not even worth considering for any team at all. Many Pokemon are better left uncaught in Johto, but these three take the cake in terms of those that actively make a team worse.
Oh, and Magcargo gets an honorary and unofficial fourth place on this list. It's just so bad that it deserved to at least be mentioned, even if it wasn't quite worse than #3.
Note: This article is subjective and solely reflects the writer's opinions.
Three new Pokemon in the Johto Pokedex to avoid
#3 - Yanma
With abilities not being introduced until Generation III and Yanmega as nothing but a distant glint on the horizon in Generation IV, Yanma possesses minimal redeeming qualities in Generation II.
Bug-Flying is an awful type combination with a multitude of weaknesses, and Yanma's stats are horrible save for speed (which still isn't all that great). It doesn't even have any exceptional moves at its disposal.
With all of the good Bug-type Pokemon in Johto, like Heracross and Scyther, there is no reason to use Yanma.
#2 - Corsola
There might be a reason to use Yanma, as it will at least get to use a move half the time before it gets KO'ed. Corsola's one somewhat decent area is its defenses, but even those are pretty miserable.
It can learn Recover, but when it's weak to powerhouse types like Electric, Ground, Fighting, and a 4x weakness to Grass, Corsola is more likely than not going to faint before having any hope of healing.
And with its abysmal speed, even if it does survive a hit, there's no chance that it's going first the next turn to heal anyways.
#1 - Unown
Anyone who has ever caught an Unown knows precisely why this Pokemon is number one on this list. It learns one move and one move only, Hidden Power. Unless players spend an inordinate time farming for the correct IVs, this move is highly likely to be completely useless.
Actually, it's likely to be useless regardless of what Hidden Power's power and type are since it'll be Unown using the move. This mystical yet ineffective Pokemon has inadequate stats that make it a laughing stock in battle.