I don't know how a comparison between Magikarp and Clefairy is even possible. The most apparent boon Clefairy has going for it is evolving right off the bat, with very respectable base stats for that point in the game, and just on time for a hard gym (Misty). Pretty much the opposite of Magikarp's situation. Gyarados does turn out to be the better specialist of the two, since its Thunderbolt and Ice Beam/Blizzard will hurt more than Clefable's.
I brought up Clefairy a little while ago, and my suggestion to move it up was rejected because it's apparently not getting any of the TMs it wants, and it's hard to find in Mt Moon. I personally think Clefable is comparable to Nidoking in much of what it does for you, minus the ground/poison typing (which can be both good or bad depending on the situation), and the whole OHKO+X Accuracy thing (should be considered for other users of these moves besides Nidoking; Tauros for instance). Nidoking won't be so effective with just Thrash and Surf, I say, you're certainly supposed to give it those TMs we agree on being "highly contested".
I brought up Clefairy a little while ago, and my suggestion to move it up was rejected because it's apparently not getting any of the TMs it wants, and it's hard to find in Mt Moon. I personally think Clefable is comparable to Nidoking in much of what it does for you, minus the ground/poison typing (which can be both good or bad depending on the situation), and the whole OHKO+X Accuracy thing (should be considered for other users of these moves besides Nidoking; Tauros for instance). Nidoking won't be so effective with just Thrash and Surf, I say, you're certainly supposed to give it those TMs we agree on being "highly contested".