This is enemy number one when deciding to build a new pauper deck.  Capable of consistent turn three kills, this traditional version of storm demands immediate answers or it will overrun you with goblin tokens and/or grape-shotting you to death.  This deck demands your opponent's answers, and fast!  Traditional storm has game against ANYTHING.

Traditional storm has been around for quite a while, and has no surprise value. From turn one, your opponent will know what you’re playing and adjust their game accordingly.  Cards like  Benevolent Unicorn, Prismatic Strands, Echoing Decay, Echoing Truth and Duress - act as a huge speed bump to a storm player's goal.  Hand disruptions and land destruction are very viable strategies toward beating this menace.  Storm can also burn out and leave itself with horrible board position and is considered quite fragile.  When playing control, the key to countering a storm player 'going off' is to counter their draw spells as much as possible.

 
This was perhaps the most hated deck in all of 2010.  It has a surprisingly good answer against both storm and goblins.  As for other decks, it can simply counter what it doesn't understand.  A fantastic deck choice when going in blind, as you have the awesome, two-island answer to everything in Counterspell.  This deck excels at answering threats during an opponent's turn and using the flash mechanic to its fullest potential.  Also, being mono-colored makes for some very consistent draws.

 

Muc's main weakness is its susceptibility to being overrun by a faster deck. The entire reason stompy (see below) emerged as a tier one deck was as an answer to muc.  Storm can be troublesome as well, as a counter or two isn't so great when running up a storm count, but cards like main-decked Echoing Truths help the odds considerably.  A strategy that works wonders against the muc player is efficient one damage spells like Flame Jab, Lava Dart, and creatures like Vulshok Sorcerer.  Basically if a card can repeatedly do one point of damage, they'll shine against this deck.

You’re almost guaranteed to face this in any tournament over four rounds, and there is good reason:  Goblins is SUPER CONSISTANT.  It comes running out of the gates swinging blood-soaked rocks and never stops.  It also has with some of the greatest main-decked powerhouse damage spells... if you’re still alive on turn five, count yourself lucky!

 
The main weakness of goblins is life gain.  Additionally red can wreak havoc on goblins too, cards like Arc Lightning, Staggershock and Firebolt can really set the goblin tempo back early on, allowing the board to develop quality blocking creatures as well as stunt the goblins growth.  If it’s turn seven or later, odds are goblins is going to lose... unless of course its opponent is at 5 or less life!  Goblins are very bad against white based life decks.  White weenie strategies are a great choice when this deck shows up in droves.

Every single deck hates the sense of dread it faces when playing against a burn deck.  Burn decks, like goblins - are VERY CONSISTANT.  Burn wins fast, so fast that if life gain wasn't of the quality it is, almost everyone would be playing burn.  Turn three kills are possible with a turn two Kiln Fiend on the board - but even without creatures, this deck is going to give your opponent a VERY fast haircut of the sulfuric persuasion! 

Like goblins, burn's main weakness is life gain and damage prevention.  If a player has no way of gaining life quickly, the advantage is all burn.  A lack of main-deck card draw (with the exception to the cantrips in the above list) -sometimes leaves a burn deck to burn itself out.  Players love to hate this deck for its ease of use, but there's no arguing its brutal effectiveness.  Answers for Prismatic Strands and Circle of Protection: Red are usually found in Flaring Pain - but running counter-answers can cost the burn player crucial turns and lack of consistency.  Often it is better to just 'be the problem.'

 
"Toolbox" is a great way to describe this deck of answers.  Teachings is a control based deck that has answers to every deck out there.  Using early game removal and/or counters, the teachings player builds their mana up to abuse end-of-turn Mystical Teachings, to search for whatever answer they need.  If allowed to enter the mid-late game, teachings is VERY hard to beat. 
 

Similar to muc, teachings can be overrun quickly by decks like goblins, stompy and affinity.  Sometimes when facing a creature light deck (like burn or storm) the teachings player will be at a big disadvantage game one due to all their main-decked creature hate.  The main knock against this powerhouse is player skill.  DO NOT play this deck without having had about 30-50 practice games against good players. Similar to playing storm, this deck isn't to be lightly considered.  The options are vast and the penalty for disregarding your teachings is a quick 0-2 record!

BANNED!  Yes, affinity is the only pauper deck out there that at one time - a card was banned!  Even after that, it is STILL nasty.  So nasty in fact, that if less artifact hate (I'm looking at you Gorilla Shaman & Smash to Smithereens) were available - I'm sure we'd see more cards from this list being banned.  Affinity comes out almost as fast as goblins, but with the big difference that these guys are 4/4's!  Air power, crazy good card-draw and access to every color of magic make affinity a top choice. 

Affinity needs artifacts badly.  So much so, that a slight disruption either by bad draw, bad luck or an opponent playing a nasty hate spell turn one or two, can send the affinity player packing.  Affinity hates to see red, as most the best anti-artifact spells are within that color.  Additionally, burn is usually a tough match-up for the affinity player.  Similar to storm, affinity’s land base is very tight and fragile - sometimes causing it to lose to itself rather than be beaten.

 
Stompy is basically "quality goblins."  Small efficient beaters with great abilities and in some cases "unblock-ability" stacked atop the best instants and creature-boosting enchantments of all time.  These help make stompy's 2/2's into 6/6's that often can't be blocked.  This deck is crazy fast and is very resilient to opposing removal strategies, even when totally tapped out via Gather Courage.  This is NOT an easy deck to play correctly.  Quirion Ranger offers some surprising complex options even with only one forest in play... so player beware!

 
Stompy has a rough match-up with storm variants.  To win, it needs to come out swinging fast and have no tempo loss.  The main reason for Thermokarsts is to get in that one more attack phase.  Teachings can put up some frustrating games vs. stompy too - unless your Silhana Ledgewalkers and/or Vines of Vastwood show up in good numbers.

Familiar storm variants are very powerful.  Some simply cast Temporal Fissure and win in the air after leaving your opponent with zero permanents in play.  Others take a more direct approach and use Grapeshot.  

All of them share the circle of abuse built upon these three cards: Snap, Frantic Search, and Cloud of Faeries.  Using any or all of these with access to one or more dual land(s) out, the familiar storm player generates obscene amounts of mana, drawing tons of cards due to the minimized cost via Stormscape Familiar(s), and then doing it all over again by temporally fissuring its own permanents like Mnemonic Wall to recover whatever it needs from the graveyard and win. 

You can tell by the sideboard what this deck fears.  Burn isn't that bad, but goblins are.  Additionally, any spells that can target your lands can be game breakers.  With no counter-magic available main deck, this deck can be easy to disrupt... but do it fast!  Turn three is key for this deck.  Also one-damage spells can put a stop on the bouncing Cloud of Faeries plan - so long as they're instants.  This style of storm is slightly slower than the traditional one, but much more consistent and forgivable, since you often bounce every permanent back to your opponent’s hand.  As with any combo deck after sideboarding, it runs the risk of losing consistency in order to have answers to any of the above problems.  A well planned--out sideboarding strategy is key.