How do I build a Pokémon TCG deck?
How do I build a Pokémon TCG deck?
Deck building 101
What's the starting point from building a deck? Before deciding on this you must have clear what actually makes a deck win games.
Consistency
I cannot stress this point enough. A consistent deck is one where every single card work towards a well focused strategy. Let's make some examples on this to explain this better.
I'll list a theme deck, say, Ice Shock from Boundaries Crossed:
Pokémon: 30

2 Black Kyurem
1 Blastoise
2 Wartortle
3 Squirtle
2 Golduck
3 Psyduck
1 Jellicent
2 Frillish
3 Pikachu
2 Electrode
2 Voltorb
1 Electivire
2 Electabuzz
2 Lopunny
2 Buneary

Trainers: 12

2 Energy Retrieval
2 Energy Search
2 Great Ball
1 Pokémon Communication
2 Switch
2 Cheren
1 Skyla

Energy: 18

11 Water Energy
7 Lighting Energy

Now, can you tell me the strategy this deck uses? Sure, one could go like &quot;let's load a lot of energy thanks to my only Blastoise and attack!&quot;. But ask yourself the following:

Where are we focusing our efforts?
What are Pikachu, Electrode, Electivire, Lopunny, Golduck and Jellicent doing here? Better yet, what is each card in this deck doing to make a win easier?
Are we ensuring we will get what we want whenever we want?

When building a deck always make yourself these questions. If a card looks cool enough with a decent effect, but you aren't sure if this will help your strategy, think again or remove it entirely. At the end of this post there's a Blastoise/Keldeo-EX deck. Let's say we think Jellicent from the deck I just listed looks cool enough for inclusion. &quot;Sure!&quot;, you might say. &quot;It's a decent card and we can still give it lots of energy thanks to Blastoise!&quot;. And maybe it might be a good idea, but what is it doing to help us win, or better yet, how does it help our main strategy, which consists of fast and powerful attacks with Keldeo-EX? Personally I see no reason for it to be here.
On that regard, the deck I listed at the bottom of the post might not be the most optimal build, but at least it keeps a level of consistency in that no card is there for no reason.
Speed
You might have a consistent deck. It can be a REALLY consistent deck. But if it's not fast enough, consistency won't win games. Speed is important. You want to take a prize before your opponent does.
Keep in mind: one Stage 2 line removes from your speed. Don't think this means you shouldn't use Stage 2 cards, but be aware that two Stage 2 lines might be too slow. Back in the DP-on and MD-on era we even had a Stadium Card (Broken Time-Space) that allowed us to evolve Pokémon as fast as we wanted, meaning we could just skip the evolution constraints. Nowadays we don't have such a card and we can just rely on Rare Candy and maybe the newer Clefable. What we can do though is to use strong Basic Pokémon, like Pokémon-EX, to speed up things. Or, we can use Stage 2 Pokémon with little energy requirements and that can hit hard, such as Garchomp and Empoleon.
Speed is important. If you don't have speed in your deck, you might have a good strategy and be pulling it decently but your opponent might have already taken two or three prizes, meaning you're already losing.
Strategy
Why would I want a strategy? I just play with my friends! And that's perfectly fine. If you're not going to play in tournaments and are completely fine with building a deck with your favorite cards and don't mind losing, it's perfectly fine. However, if what you want is to take a step forward, then a strategy is a must.
For choosing a strategy, choose a combination of two or more cards. Some good combinations are Eelektrik and Zekrom (Zekrom discards [L] energies you can retrieve with Eelektrik), Gabite, Garchomp and Altaria (Gabite searches for [D] Pokémon, Garchomp hits 60 for [F] and Altaria is a [D] Pokémon that adds 20 damage to [D] Pokémon when in play), Empoleon and Emolga (Emolga fills your bench and Empoleon deals damage with [W] and adds more damage the more Benched Pokémon you have, plus it lets you draw two cards by discarding one) and Blastoise and Keldeo-EX (which I'm going to talk about now).
Choosing a strategy
The first thing you should ask yourself is: &quot;How do I want to win?&quot; Let's double check the possible ways to win a game, since that's what you build your deck for.
You win a Pokémon TCG game by fulfilling one of the following conditions:

Defeat all of your opponent's Pokémon. This means, when you knock out your opponent's active Pokémon, your opponent should not be able to move a benched Pokémon to an active position.
Draw all your prizes. Usually this means defeating six of your opponent's Pokémon, but Pokémon-EX allow you to draw two cards and &quot;Lugia-EX&quot; allows you to draw an extra prize, so did &quot;Rayquaza &amp; Deoxys LEGEND&quot;. Also there are cards that can increase the amount of prizes your opponent has to take.
Your opponent cannot draw a card at the start of his or her turn. Keep in mind this does not apply to other effects that would allow you to draw cards. For instance, &quot;Professor Juniper&quot; states that you must draw 7 cards from your deck. If you have less than that, you draw all of them and it doesn't cause a game loss condition; you only lose if you cannot draw a card at the start of your turn.

Keeping all of this in mind, we must choose one or more ways to win. For the sake of simplicity (and because most decks use this as a basis), we will use the first two winning conditions.
Choose a combination
The best way to see what cards would allow us to win in the way we've chosen, we must find a combination of two or more cards that would let us win in the fastest way possible. Why fastest? In the current format (BW-on), speed is important. There are so many Pokémon-EX we cannot just ignore speed. We must hit hard and fast before our opponent get a chance to use their Pokémon! And this doesn't just apply to Pokémon-EX but to any metagame. Even in the old days of Base Set/Jungle/Fossil we had to deal with this, namely the Haymaker deck which won many games hitting fast and hard.
There's a combination we can use for a simple deck (keep in mind this combo is actually being used): Blastoise (Boundaries Crossed) and Keldeo-EX. Why?

Blastoise - 140 HP - W
Stage 2 - Evolves from Wartortle
Ability: Deluge

As often as you like during your turn (before your attack), you may attach a [W] Energy card from your hand to 1 of your Pokémon.

[C][C][C][C] Hydro Pump - 60+

Does 10 more damage for each [W] Energy attached to this Pokémon.


So, it's a Pokémon that allow us to attach as many [W] energy as we want to our Pokémon! Now let's see Keldeo-EX:

Keldeo-EX - 170 HP - W
Basic Pokémon
Ability: Rush In

Once during your turn (before your attack), if this Pokémon is on your Bench, you may switch this Pokémon with your Active Pokémon.

[C][C][C] Secret Sword - 50+

Does 20 more damage for each [W] Energy attached to this Pokémon.

Pokémon-EX rule: When a Pokémon-EX has been Knocked Out, your opponent takes 2 Prize cards.

So, the idea is: we take out Blastoise, draw as many [W] energies as we need, attach them to Keldeo-EX and use Rush In to make it active. Great synergy!
Building the core
Now that we've decided our core strategy, we must now build the basic core! Just keep in mind we cannot place more than 4 cards of each type, except for Basic energies. Let's do it!
Pokémon: 16

4 Squirtle (BC)
4 Wartortle (BC)
4 Blastoise (BC)
4 Keldeo-EX (BC)

Why 4 of each? Not only this is our core, but the cards we will be using the most. It's only natural we want the most of them!
But, do we really want 4 of each?
Firstly. How many Blastoise do we need in play? Only one. So maybe four Blastoise is a bit overhead. We can try reducing this to a smaller core (keeping four Squirtle in case of being catchered [Pokémon Catcher allows you to switch our opponent's Pokémon with any other of his or her bench]):
Pokémon: 16

4 Squirtle (BC)
3 Wartortle (BC)
3 Blastoise (BC)
4 Keldeo-EX (BC)

We can still reduce the Wartortles with help from Rare Candy, which lets us evolve one of our Basic Pokémon to its Stage 2 card. If we include all four Rare Candies we can reduce Wartortles to just one (and one to avoid Item locks such as Gothitelle, which wouldn't allow us to play that card):
Pokémon: 12

4 Squirtle (BC)
1 Wartortle (BC)
3 Blastoise (BC)
4 Keldeo-EX (BC)

Trainers: 4

4 Rare Candy

It's still 16 cards, but now we can have Blastoise at turn 2 and be ready to attack. It's way faster than what we had before!
Supporting cards (not Supporter cards though)
Now that we have our core, we must focus on cards that will support our main strategy. Do not confuse the title with Supporter cards. We will add them here but I'm not talking exactly about these.
What do we need to take these Pokémon as fast as possible? Here you can be creative and add whatever cards you would think will help the strategy. I'll describe some cards you should consider when building a deck (and that might be useful for this particular deck):

Computer Search: An ACE SPEC card (meaning we can only have one of them and no other ACE SPEC card) that allows us to discard two cards and search for any other card in our deck.
Gold Potion: Another decent ACE SPEC card that heals 90 damage from one Pokémon.
Great Ball: An Item card that lets us look at the first seven cards of our deck, choose a Pokémon from there and place it in our hand.
Heavy Ball: Another Item card that lets us search for a Pokémon with a Retreat Cost of 3 or more. Blastoise has 4 so we can consider it.
Professor Juniper: A Supporter card (we can play one of these during our turn) for discarding our hand and drawing seven new cards. Good for hand refreshing, also a staple.
Cheren: Draw three cards. Straightforward.
Bianca: Draw a card until you have six in your hand.
Eviolite: Keldeo-EX will love these. A Basic Pokémon with this tool attached will receive 20 less damage from any attack.
Rescue Scarf: Another card for Keldeo-EX. If you don't worry that much about damage, consider retrieving them when they get KO'd.
N: Supporter. Each player shuffles their hand on their deck and draw one card for each prize card remaining. Good disruptor.
Random Receiver: Item, reveal one card from your deck until you find a Supporter. Good in a pinch.
Skyla: Search your deck for any Trainer card.
Ultra Ball: Discard two cards from your hand and search for a Pokemon in your deck.
Super Rod: Search for three cards in any combination of Pokémon and Basic Energy cards and shuffle them in your deck. A good recovery card, include at least one of these in your deck.
Pokémon Catcher: Switch your opponent's Active Pokémon with a Pokémon on his or her bench. A must for every deck, 3 or 4 will do.
Pokémon Communication: Change one Pokémon from your hand with one from your deck.

If you notice, Trainer cards can be roughly classified as:

Hand refreshing: They allow us to refresh our hand. You must have some of these in every deck. Juniper and N are examples of this.
Drawing: They draw more cards for us to have mor play options. Bianca and Cheren do this.
Searching: They let us search for specific cards. Skyla and Heavy Ball are examples of this.
Disrupting: They alter the way your opponent plays, such as N and Pokémon Catcher.
Recovery: They help us retrieve things that were discarded, or to turn around the table when things look bad. Super Rod, and in a certain way, N, are excellent for this.
Combat: They help us during combat, when receiving and dealing damage. Gold Potion and Evolite do this.

All in all, we shouldn't just include one of each and be done. What we must be pursuing is consistency. Our deck must be able to pursuit the goal we've defined before in all times and each and every card must help with this. Keeping all of this in mind, I've decided to include the following cards:
Pokémon: 12

4 Squirtle (BC)
1 Wartortle (BC)
3 Blastoise (BC)
4 Keldeo-EX (BC)

Trainers: 29

4 Rare Candy
1 Computer Search
2 Ultra Ball
4 Great Ball
2 Super Rod
4 Cheren
3 Bianca
3 N
4 Pokémon Catcher
2 Skyla

29 trainers?! Isn't it a bit excessive? No. Actually no. Most of your deck should consist of Trainers, believe it or not.
Completing the deck and adding other cards
We have a solid deck but we're lacking two other things:

Energy Cards
Techs

What's a tech? It's a card we include in order to deal with threats to our deck! What can threat our deck SO much???

Mewtwo-EX: The more energy cards we have attached, the more damage we will receive thanks to X Ball. We must deal with this somehow!
Sigilyph: It basically nullifies our Keldeo's attacks.

Sigilyph can be easily dealt with: We load a Blastoise with energy, retreat a Keldeo, and send it to attack. A Blastoise with [W][W][W] attached will KO it in no time. The real problem is Mewtwo-EX. Sadly the best way to counter it is with another Mewtwo-EX. So, we will include two of these.
Now we have 43 cards in our deck. How about adding three more cards? I would bet for Energy Retrieval, which recovers two Basic Energy cards from our discard pile. So adding three of these will be great. The remainder of the deck will be water energies - limit yourself to no more than 18 Energy cards and that's for a deck that actually needs many of them.
The final deck
Pokémon: 14

4 Squirtle (BC)
1 Wartortle (BC)
3 Blastoise (BC)
4 Keldeo-EX (BC)
2 Mewtwo-EX

Trainers: 32

4 Rare Candy
1 Computer Search
2 Ultra Ball
4 Great Ball
2 Super Rod
4 Cheren
3 Bianca
3 N
4 Pokémon Catcher
2 Skyla
3 Energy Retrieval

Energy: 14

14 Water Energy

Conclusion
We've gone through building a deck from the very core of it to an actual full fledged deck. Keep in mind this might not be an optimal build, but I think it's enough to illustrate the point and to help starters getting going with their very own deck.