OK, found it.
Ubers - Pokemon that are too powerful in a competitive setting, and are thus banned under most conditions.
Arceus
Darkrai
Deoxys (All forms)
Dialga
Giratina
Groudon
Ho-oh
Kyogre
Latias
Latios
Lugia
Mew
Mewtwo
Palkia
Rayquaza
Wobbuffet [Banned]
Overused - The most dangerous pokemon in competitive play.
Aerodactyl
Alakazam
Azelf
Blissey
Bronzong
Celebi
Cresselia
Dragonite
Dugtrio
Dusknoir
Electivire
Garchomp
Gengar
Gliscor
Gyarados
Heatran
Heracross
Infernape
Jirachi
Jolteon
Lucario
Manaphy
Medicham
Metagross
Porygon-Z
Raikou
Regice
Rhyperior
Salamence
Shaymin
Skarmory
Slaking
Snorlax
Starmie
Suicune
Swampert
Tangrowth
Tauros
Togekiss
Tyranitar
Weavile
Yanmega
Zapdos
Borderline - Pokemon that are outclassed, not particularly threatening, or overly powerful for the Underused category. Most of these are still useful pokemon.
Ambipom
Arcanine
Armaldo
Articuno
Blastoise
Blaziken
Breloom
Charizard
Claydol
Cradily
Crobat
Dodrio
Donphan
Drapion
Empoleon
Entei
Espeon
Exeggutor
Feraligatr
Floatzel
Flygon
Forretress
Gallade
Gardevoir
Honchkrow
Houndoom
Jumpluff
Jynx
Kingdra
Lapras
Leafeon
Lickilicky
Lopunny
Ludicolo
Machamp
Magmortar
Magnezone
Mamoswine
Marowak
Mesprit
Milotic
Miltank
Mismagius
Moltres
Muk
Ninetales
Ninjask
Omastar
Porygon2
Probopass
Rampardos
Regigigas
Regirock
Registeel
Roserade
Sceptile
Scizor
Shuckle
Slowbro
Smeargle
Spiritomb
Staraptor
Steelix
Swellow
Tentacruel
Torterra
Toxicroak
Typhlosion
Umbreon
Uxie
Vaporeon
Weezing
Underused - Pokemon that are not threatening or particularly useful in most cases.
Abomasnow
Absol
Aggron
Altaria
Ampharos
Ariados
Azumarill
Banette
Bastiodon
Bellossom
Cacturne
Camerupt
Carnivine
Clefable
Cloyster
Corsola
Crawdaunt
Dewgong
Drifblim
Dunsparce
Electrode
Exploud
Fearow
Flareon
Froslass
Gastrodon
Girafarig
Glaceon
Glalie
Golduck
Golem
Gorebyss
Granbull
Grumpig
Hariyama
Hippowdon
Hitmonchan
Hitmonlee
Hitmontop
Huntail
Hypno
Kabutops
Kangaskhan
Kecleon
Kingler
Lanturn
Linoone
Luxray
Magcargo
Manectric
Mantine
Meganium
Mr. Mime
Nidoking
Nidoqueen
Noctowl
Octillery
Phione
Pikachu
Pinsir
Poliwrath
Politoed
Primeape
Purugly
Quagsire
Qwilfish
Raichu
Rapidash
Relicanth
Sableye
Sandslash
Scyther
Seviper
Sharpedo
Shiftry
Skuntank
Slowking
Stantler
Sudowoodo
Swalot
Torkoal
Tropius
Ursaring
Venomoth
Venusaur
Vespiquen
Victreebel
Vileplume
Wailord
Walrein
Whiscash
Xatu
Zangoose
Never Used - You'll see these once in a blue moon: The worst of the worst.
Arbok
Beautifly
Beedrill
Bibarel
Butterfree
Castform
Chatot
Cherrim
Chimecho
Delcatty
Delibird
Ditto
Dustox
Farfetch'd
Furret
Illumise
Kricketune
Ledian
Lumineon (Neorant) =D
Lunatone
Luvdisc
Masquerain
Mawile
Minun
Mightyena
Mothim
Pachirisu
Parasect
Persian
Pidgeot
Plusle
Raticate
Rotom
Seaking
Shedinja
Solrock
Spinda
Sunflora
Unown
Volbeat
Wigglytuff
Wormadam
Source:
Neoseeker Forums