Venusaur: Chlorophyll + Growth = +2 Atk, SAtk, and Spd within 1 turn = Sweep
Blastoise: Could work as a lead since it has Fake Out, Aqua Jet, etc, with sufficient bulk to take on pretty much anything else and stop set-up leads with rapid spin
Charizard: Solar Power + STAB + Specs = Most powerful thing to blast stuff really hard.
Meganium: Leech Seed, Dual Screens, Counter, Aromatherapy, etc = Support
Feraligator: More Powerful Gyarados with it's DW ability, without the 4x weakness
Typhlosion: Eruption = Overpowered.
Sceptile: Subseed
Swampert: What else d'ya want?
Blaziken: He's freakin' banned from OU D:
Torterra: Anything that tries to Ice Beam you will be KOed switching in anyway
Empoleon: You don't want to know how good this guy pairs with Zapdos
Infernape: Anti-lead, SD/NP Sweeper, blahblahblah
Serperior: Yeah, he's overpowered after 3 Leaf Storms.
Samurott: Awesome movepool, wall breaker
Emboar: Ok this guy is awesome when it comes to breaking walls. better than blaziken last gen. I think.
...
Staraptor: Life Orb + Brave Bird/Double-Edge recoil x2 = 20% HP. Endeavor then, and yeah. @Down: It's not a strategy at all. Just a theory. Still gotta test it
Ideally I switch in with my 20%, and while he switches to his wall, Wham, and they are at 20%
All the starters have Water Pledge and ETC, not to mention those Hyper Beam- style moves (Which are crap, so don't use them).