Magikarp by far.

If you read magikarp's entry in D/P's pokedex it says it is the weakest Pokemon.

magicarp not pidgey!!
pidgey can actually tackle (later games) or use gust (older versions)
while magikarp can just splash around like a gay fish.
but once it evolves its good.

yeah thanks for making me feel bad...

i'll keep it for futrue reference though. 

 But Abra with Psywave, Seismic Toss and Mega Punch is one of my main 6!

 Using TMs shouldn't be discounted.

It depends. A level 100 Magikarp can defeat a level 70 Mewtwo, depending on what attacks, both Pokemon know. If the Pokemon are at an equal level, then it comes down to Caterpie, Metapod, Weedle, Kakuna, Ditto, Abra, and Magikarp. Magikarp learns Flail, and if used correctly, can do a lot of damage. Metapod, and Kakuna can learn tackle, but if caught in the wild, they can only Harden, which is pretty useless, since they can't attack. Abra can Teleport, but not out of a trainer battle, so in a trainer battle, Abra is useless. Ditto is as strong as the opponent, so faced against a Magikarp, they are evenly matched.

weezing, ekans and meowth they never win

trying to remeber 10 years ago....

o yes pidgey. that bird pokemon. i swear he always used to get raped by bulbasor.

Pichu

Magikarp and Abra...




...Stupid Teleport...