One of the most common memes on the GameFAQs Pokemon message boards are to ridicule any poor prole who dares to ask for help with their ingame team. Basically, "everything works ingame".
But if all Pokemon are equal, some are clearly more equal than others. And all things considered, these are one man's best bets if he needs to do a speedrun and chuck his starter.
10) Ramprados (Diamond, Platinum)
Despite how much of a pain he is to raise as a Cranidos (and to get, especially in Platinum), bear with me. Because of the way his experience curves, as the levels increase he levels up faster and faster. His main feature is Mold Breaker, though - you have no idea how much easier the Galactic double battle is when you can laugh at the Bronzor and their Levitate. He's just fast enough to avoid being a complete glass cannon...
9) Lapras (Fire Red/Leaf Green)
Sure, it's somewhat late to the party - but when it gets there, it turns everything upside down and all for the low price of a little leveling and a quick visit to Mr. Psychic's house. During the Silph Co run it'll level to the point of learning Body Slam and Ice Beam on its own, and it tears the back half of the game apart.
8) Zigzagoon (Ruby/Sapphire)
The only Pokemon on this list not in it for their ability to tear things apart - but the original Pickup distribution giving you Nuggets, Rare Candies and Hyper Potions off your first Pokeball? I'll take five, thanks.
7) Machamp (Gold/Silver/Crystal)
Strictly on the list for the purpose of survival against Whitney and that damn cow of hers. And even after that, he's growing 1.5x faster than the rest of the team so you might as well let it hang around. There's a Dig TM right after that so you can even use it against Morty. (Shame this won't happen in the remakes, stupid Levitate).
6) Nidoking (Red/Blue/Yellow)
It's amazing how much a quick evolution can help you. In Nidoking's case (L16 + a Moon Stone and you get two in Mt Moon) it almost triples Nidoran M's TM capability, and it learns enough of the expendable TMs to have a hell of a lot of move variety. Despite being nasty, it's not as evil as...
5) Dugtrio (RBY)
You should never need to use a starter against Surge, and here's why. Thanks to the way RBY criticals function, Dugtrio got double damage about 30% of the time with that insane speed, and it had Slash (a high CH move). Dig getting downgraded and not having Magnitude in FR/LG cost him a top 3 spot.
4) Butterfree (FR/LG)
If you're trying to play it somewhat straight (weaken, sleep, throw) then Butterfree is your god and it's all thanks to 98% accurate Sleep Powder. He's not a killer, but he's a crippler and probably the best crippler in the history of the game (ingame).
3) Golem (GSC)
The perfect combination to beat GSC quickly: The Geodude family to start, then finish with #1. You get it early and Rock Throw beats the first two gyms, at which point you get Magnitude to take everything out. Bonus points for a natural Earthquake. Although the last two gyms give him pause, he's still damn lethal. Don't believe me? Ask the speedrunners.
2) Staraptor (DPPt)
It's like they took every complaint about the early-game Flying types and made the ultimate Flyer. Intimidate and jacked up attack/speed keeps him tearing things apart and he could feasibly be used against every gym except the first and last. Throw in Close Combat and Return (he's an amazing candidate for the bonus Return TM in Platinum) and it can even beat the Rocks and Steels that stop a typical Flyer cold.
1) Alakazam (GSC)
The math is simple:
1 Abra + $9,000 = broken.
It's so easy to raise Abra when you have three base 75 special moves available for purchase in the city next to where you catch it. And Alakazam's Speed and SA are both high enough that no matter what, he's going to go first and probably take something out as you move up the chain of Psychic moves. Did I mention he can beat the Elite 4 on his own except for two Pokemon (Umbreon, Houndoom)?