LOL...
Sorry, but no matter how so-so Charizard is, you can't compare it with such weaklings. Though I guess ~*CB*~ will have a field time as soon as he sees this.
As far as I'm concerned... Sunkern has the lowest Base Stats total of all Pokémon, which means the lowest Stats overall. However, its Movepool, while badly limited to Grass attacks, is half-decent. Magikarp has a Speed worthy of notice (Able to outspeed even a handful of fully evolved Pokémon.), and while its other Stats suck badly, it can do something like OHKOing Deoxys Attack Form with a full-power Flail.
In my opinion, Caterpie is the worst of the bunch. It's got an awfully limited Movepool (Tackle and String Shot...), and while its Stats are certainly MUCH better than those of Sunkern, they're not of much use with the worst Movepool ever. Weedle gets Poison Sting, which can be helpful in a pinch at the very least. Caterpie, to quote some Bug Catcher in RBY, just doesn't cuts it...