In Layman's Terms

Courtesy of a post on the Old Wizards forum, credit, as posted by SwampertEX on pokegym.

NRG - Energy
Para - Paralyzed
PKMN - Pokémon
PSN - Poison

HP - Hit points or Health Points
PP - Pokemon Power

C - Colorless (Energy card / Pokémon type)
D - Dark (Energy card / Pokémon type)
F - Fighting (Energy card / Pokémon type)
G - Grass (Energy card / Pokémon type)
L - Lightning (Energy card / Pokémon type)
M - Metal (Energy card / Pokémon type)
P - Psychic (Energy card / Pokémon type)
R - Fire (Energy card / Pokémon type)
W - Water (Energy card / Pokémon type)

Darkness - Dark (Energy card / Pokémon type)
Evil - Dark (Energy card / Pokémon type)
Steel - metal (Energy card / Pokémon type)

BS - Base Set
TR - Team Rocket
GH - Gym Heroes
GC - Gym Challenge
NG - Neo Genesis
Neo1 - Neo Genesis
ND - Neo Discovery (disaperas when Neo Destiny is released?)
Neo2 - Neo Discovery
NR - Neo Revelations
Neo3 - Neo Revelations
Neo4 - Neo Destiny
SI - Southern Island
Black Star Promos - Series of consecutively numbered promo cards. These include the Pokemon TCG cards given away at the Movies (except Ancient Mew) and earned in tournaments (reverse holo Rainbow energy isn't numbered either).
Ex- Expedition
Aq-Aquapolis
Sk-Skyridge
R/S-Ruby & Sapphire
SS-Sandstorm (Note: another abbreviation for Sandstorm is Sand.)

CPU - Computer Search
DCE - Double Colorless Energy
Elm - Professor Elm
ER - Energy Removal
FHE - Full Heal Energy
GB - Gold berry
GOW - Gust of Wind
HCTR - Here comes team rocket!
IF - Item Finder
IOR - Imposter Oak's Revenge
LSSM - Lt. Surge's Secret Mission
NGR - Nightly Garbage Run
Oak - Professor Oak
TRT - The Rocket's Trap
PE - Potion Energy
PP - Plus Power
PTC2007 - Pokémon Trivia Contest 2007
RSA - Rocket's Sneak Attack
RTrap - The Rockets' Trap
SER - Super Energy Removal
TV- Town Volunteers

'Buzz - Electabuzz
'Canine - Arcanine
DVile - Dark Vileplume
Feral - Feraligatr
'Gatr - Feraligatr
Rk9 - Arcanine
RZap - Rocket's Zapdos
M2 - Mewtwo
Mew2 - Mewtwo
MPM2 - Movie Promo Mewtwo
NPM2 - Nintendo Power Mewtwo (w "Telekenesis")
Sab's - Sabrina's
T-Tar - Tyranitar
'Tuff - Wigglytuff

BBP - Big Basic/Bad Pokemon
FTK - First Turn Kill
FTKO - First Turn Knockout
KO'd - Knocked out
OHKO - One Hit Knockout

GB - Game Boy
00ber - Pokemon in GB game of exceptional power and capabilities, normally considered as a 'cheap' method of winning when used in battles.

CCG - Collector Card Game
TCG - Trading Card Game
RPG - Role Playing Game
Appr - Apprentice; A free download that lets you play Magic the Gathering over the internet, which can be fixed to play Pokémon TCG with the aid of a special patch.
DCI - Duelist Convocation International
HP - Harry Potter
MtG - Magic the Gathering
MT's - Master Trainers (the Wizards employees who run the chats, issue rulings and put together all the various Wizards-sponsored Pokemon events)
PA! - Pokemon Aaah! (website containing, among other things, fan made fake Pokémon TCG cards)
Pojo - The magazine writers/website designers for pojo.com, who were responsible enough to sustain and keep up with the interest in Pokémon with articles and deck reviews (now defunct)
PIRN - Pokémon Internet Radio Network
RTC - Random Topic Center
Weekly ruling chat - Chat held every week on Wizard's chat host on thursdays from 3-5 (Pacific time).
SoCal - Southern Californian team
TC - Team Compendium (the guys who maintain the online Rules Compendium)
TE - Team Europe member
TO - Tournament Organiser
TPC - The Pokémon Company
WotC - Magicians near the sea? http://archivedboards.wizards.com/tcg/wink.gif Wizards of the Coast
Zeo - Pokemon Zeo (website containing, among other things, fan made fake Pokémon TCG cards)

BDS - Big Daddy Snorlax
DMTM - Dark Master Trainer Mike
DAS - Dark Aprentice Steve
'Mom - SD_Pokemom
MTM - Master Trainer Mike
MTP - Master Trainer Pat
'Pop - PokéPop
'Sensei - PokéSensei

Mize - To completely crush the oponent.
n00b - A player unexperienced in the game.
Scrubs - A player who engages in a number of bad behaviors. Most scrubs are new players, but some are experienced. Some of the bad behaviors are deck copying, bad sportsmanship, and whining about "broken" cards in Pokemon (seriously).
Veteran - A seasoned knowledgable player of Pokémon

15/3 format - A format tried at the ECSTS 2000. Decks were restricted to 15 trainers (unlimited in other formats) and no more than 3 cards of one type (4 in other formats). Wasn't well recieved and therefore scrapped.
Draft format - Players don't bring their own deck to the tournament, but are given booster packs and can borrow basic energy cards at the venue. The players (preferably 8) sit down at a table with 5 booster packs each of Pokémon cards. Packs should be from two different sets that compliment each other (Base 2-only drafts also work fine). Meaning they have evolution chains that work for both sets. All players open their first pack of cards at the same time. Everyone then takes one card from the pack they just opened and passes the rest of the cards in that pack to the person on their right who picks a card and passes the rest on to the right etc until the cars run out (Basic energy cards are discarded). Then the players open a second pack and repeat the process, but this time passing to the left instead of the right. Deck size is smaller than ususal (40 cards - 4 prizes).
Modified format - Also known as the E-on (Expedition-on) format. Cards that were released prior to the Expedition exspansion are not allowed in this format, but anything after that is fare game, except and promo's of said cards. Black Star Promo's are not allowed (except for the numbers 001-on). Re-released cards are aloud (ie, Switch, Potion etc.).
Unlimited- All cards except Birthday Pika and Anciect Mew
STS - Super Trainer Showdown
STSQ - Super Trainer Showdown Qualifier
ECSTS - East Coast Super Trainer Showdown
WCSTS - West Coast Super Trainer Showdown
Professor - a professional/15+ player that has undergone a specific test to become a Professor. ("Professional Pokémon TCG player"?)
711 - The room you (originally Seena Ghazaiskar and Matt Moss?) stayed in at hotel when you've won a major tournament

Baby Killer - An attack or Pokémon that can damage an opponent's benched Pokémon for 30 or more damage.
Broken Card - A card that "breaks" the carefully balanced playing environment in a TCG. In theory, any card that exceeds the average power given its circumstances. In practice, it refers to cards that have severely disporportionate power compared to the amount of effort needed to play the card. Neo Genesis Sneasel is by many regarded as a broken card (at least in the Modified format), but not everyone agrees with this. Among certain players, broken is simply used to mean "really good or effective".
Crutch - An easy to use card, particularly when such cards are heavily used. NG Sneasel is a perfect example. The term is derived from the fact that a player depends on the crutch cards to carry their bad deck to victory, much like a person uses a real crutch to carry themselves around on a bad leg.
Metagame - What everyone is playing in the area in question. If a good deck(type) is established, other "counter"-decks will develop to try to break the dominance.
Pull - Slang for getting a card in a booster (e.g. "I pulled a 1st Ed. Charizard!!!")
Tech - A card that is put in a deck in a quantity of 1 or 2 to deal with specific threats (such as putting in Pichu to a non-PP deck to deal with common PPs or Wooper/Magmar in a Grass deck to deal with Weakness/Resistance).
Undermetagamed - When a decks against a certain dominating decktype haven't been developed so that the dominating deck is able to run rampant.
Whammy - A card that does major Energy damage (Hoo-hoo... How about Super Energy Removal, Misty's Golduck, or Shining Gyarados?)
Bling-Bling- Reverse Holofoil

Archetype deck: A particular distinctive type of deck. There may be a vast ammount of different ones but they'll all have the same core strategies, i.e. Raindance.
Precon: Preconstructed Deck, which Wizards of the Coast usually releases with a new expansion to demonstrate new mechanics.
Rogue deck: A deck that not only isn't an archetype, but is deliberately trying to do something different and unexpected.
Xerox deck: A deck which is a blatant copy of one found in numerous online deck garages/listings

Below are few archetype decks, more have been mentioned, but I'm only listing the "major" and well defined decks.

Big Fire deck: A Big Fire deck usually refers to one based on Blaine's Arcanine who has a huge 120 point attack and uses the Fire Recharge Typlosion.

Feral deck: Based around Feraligatr (DownPour) together with Trash Exchange, Misty's Wrath, Double Gust & Focus Band. The idea is to keep moving water energy cards to the discard pile, as the Feraligatr attack "Riptide" does 10 damage plus ten times the number of water energy cards in the discard pile. After the attack the Water energy cards in the discard pile are shuffled into the deck... A subvariant is Gatrsect deck that uses Neo Revelations Parasect which has a Pokémon Power that makes all cards stay in the discard after Riptide.

Cleaner / Turbo Pup Deck: Centered around Arcanine's attack Take Down. Sometimes Canine is brought out early and healed w/ Gold Berry while consistently using Take Down. Pokemon: Growlithe, Arcanine, Fossil Magmar, Electabuzz, R. Oddish( sometimes), Scyther, Rocket Zapdos, Lickitung, Ditto, etc.

Haymaker deck: Focuses on big basic Pokémon (BBP) with quick, energy-efficient attacks and relatively high HP. It was named after Hitmonchan, the original basis of the deck, "Haymaker" is Hitmonchans first attack when translated from Japenese. (A haymaker is a general term for a Knockout punch in boxing.) Main Pokemon: Hitmonchan, Scyther, Electabuzz, Sneasel, Gligar, TR Zapdos, Fossil Magmar, Sometimes TR Scyther, Farfetch'd. A subvariant is the Sponge deck which includes Movie Promo Mewtwo.

Mindgames deck (or Dunce deck) : Use Slowking and Chaos gym to make the opponent have a 25% of playing trainers and often giving you the trainers. You have a 50% of playing trainers but that's better than none.
Main Pokemon: Cleffa, Sneasel, Chansey, Slowking, and Slowpoke.

Raindance Deck: A Raindance deck is a Water-type deck based around Blastoise, and other Water Pokémon with attacks that do a lot of damage. The main focus is to use Blastoise's Pokémon Power to get a lot of energy on Pokémon like Dewgong, Articuno, and Gyarados as fast as possible. The deck was named after Blastoise's Pokémon Power, Rain Dance. Main Pokemon: Blastoise, Squirtle(preferably TR), Fossil Articuno, Lapras, Ditto.

Sir-Flip-A-Lot: Deck abusing Giovanni's Machamp and Focus Band.

Stall deck: Uses high HP Pokemon like Chansey and Lickitung to stall while maxing out on (Super) Eenergy Removal, Scoop Up, Pokémon Center, and Item Finder. Tries to deck the opponent. Moltres is usually included to make the opponents deck even faster, and to get rid of important anti-decking cards like Lass and Nightly Garbage Run. Fossil Magmar, Erikas Dratini, and Scyther are also common.

Trap Deck: Meant to leave your opponent with little or no options on their first turn by using The Rocket's Trap, Imposter Oaks Revenge, and Rocket's Sneak Attack, other variants uses Aerodactyl, Dark Vileplume, Murkrow .

Crack Monkey: an impossibly strong deck. i.e. Sneaking.

Ungodly Luck: When a weenie knocks out a fully powered up Uuber. IE When a Dunsparce flips seven heads and KO's a fully powered up Blaziken ;)

POR - Professor Oaks Research
1337 - (leet)Elite - masterful
Bex - Blaziken EX
Cune - Suicune EX
NEO - North East Ohio (Elite Playing Region)
Chaw - greeting or substitute for random curse word
PUSA - Pokemon USA, Also PUI
pwn - utterly destroy; also means own. I.E. That deck pwns!
topdeck, or Yugi - get a great card at the top of your deck
CC - Copycat
woot - a random cheer
Zuver - to say something utterly mysterious, yet deep, also Zuverese; referring to Douglas Zuver, a Florida Professor...
Mods - those running the board
TC - Team Compendium (Rules gurus and recorders)
DR- EX-Dragons
AvM, TATM, TAvTM- EX-Team Aqua vs. Team Magma
HL- EX-Hidden Legends
Gex- Gardevoir EX (Also Gardex)
Rex- Rayquaza EX (Also RayRay and 'Quaza)
Sex- Me, AKA Swampert ex
Eon- Current modified format
Exon- No, not a gas station, next Modified format, R/S and up
Kitty- Skitty
Catty- Delcatty (Energy Draw)
BAR- Blaziken/Ampharos/Rayquaza
Wobby, Wobbers, >_<- Woboffet (Sand Storm)
Prerelease Raichu: Supposedly the rarest card, next to one-of-a-king cards given away to the winners of major Japanese Tournaments and the like. ie "Or is that as hard to find as a Pre Rai?"
Whiscash: A flawed/flawless (depending on who you ask ;p) counter to Blaziken ex. It is usually used when someone is either trying to think of a way to counter the Blaziken variant, or is using a very sub-par deck. (ie omg this sucks. Go play Whiscash)
Mex: Metagross Ex
Phanpy/Teddiursa/Pichu: Three Pokemon plush dolls given out to the winners of City Championships. Used along the lines of pseudo-topdecks, and even jokes
BW: Backwash (program on apprentice for stacking the deck)
Mize - To completely crush the oponent.
PETM: Professor Elm's Training Method
Net Deck- A deck copied straight of the internet.
Crobyss: A deck consisting of Crobat (HL) and Gorebyss
Metabyss: A deck consisting of Metagross(ex) and Gorebyss
BaDMoM: A deck consisting of Blastoise ex, Catty, Milotic, and Magneton
Rambo: Rayquazza ex, Aqua's Manectric, Blaziken ex, One Hit Knock Out.