You said you're new right? I’m gonna help you understand the format and the competitive scene.
First of all decks look kinda like this 10 pokemon 10 energy 40 Trainers ( around ). You normally build a deck around just one pokemon. And there are certain pokemon that are good i will list those in the next Also there is something called format rotation. This is when cards have gotten too old and they go to a different format. In standard ( right now ) we have primal clash , Roaring skies , Ancient Origins , Breakthrough , Breakpoint , Fates collide , Stream Siege , Evolutions. In expanded we have : Black and white , Emerging Powers , Noble victories , Next Destinies , Dark Explorers , Dragons Exalted , Boundaries crossed , Plasma storm , Plasma freeze , Plasma Blast Legendary treasures , Xy base , Flashfire , Furious fists , Phantom forces , Primal clash , Roaring skies , Ancient Origins , Breakthrough , Breakpoint , Fates collide , Stream Siege , Evolutions. Expanded has more sets and I suggest starting off with it.
Decks to use
Standerd
This is where i'm not very great but i know what it is. These are four decks that are great in standerd
Mega Ray
In mega Rayquaza you deal 30x the number of pokemon you have on your bench and with the card Sky Feild you can have 8 pokemon on your bench meaning 240 damage cap.
Mega Gardy
In mega Gardevoir you discard your pokemon to deal extra damage
Greninja Break
This deck uses Greninja Breaks Ability to snipe Your opponents shaymin ex.
Valcion
This deck Uses Valcain ex abilty to power up some fire attackers like …… Vailcaion
( i'm sorry i can't spell this things name for my life )
In expanded The format is
Night march
This deck uses battle compressor to deal 180 damage or more very easily
Trev
Locks your opponents out of using items. Which pretty much wins the game ( i will explain in the next subheading thing )
Yveltal
This deck destroyed by flooding energy onto all of your Pokemon
Cards that are a virtue to every deck
In every good deck you need the cards i am about to list.
Shaymin ex ( roaring skies )
Excluding Greninja . Every deck needs to draw without using a supporter. ( as you can only use One per turn ) and SHaymins ability lets you draw cards until you have 6 in your hand.
N ( Fates collide , noble victorys )
A very game changeing card. It can be risky but it pays of more of the time
Each player Shuffles Their hand into their deck and draws cards equal to the amount of prize cards they have remaining
Professor Sycamore ( xy base , Breakpoint , Phantom forces , Steam sige )
Sometimes you are just looking for one card that can win you the game. And this card will help you find that one card.
Discard your hand and draw 7 cards
Lysandre ( Flash fire , Ancient origins )
Sometimes you need 2 more prizes to win the game. You play this card to knock out your opponents Shaymin ex
Vs seeker ( Phantom forces )
I think the description of what the card does will teach you why it's good.
Put a supporter card from your discard pile into your hand.
Acro bike ( primal clash )
Sometimes you are just looking for one card that can win you the game. And this card will help you find that one card.
Look at the top two cards of your deck put one into your hand discard the other.
Trainers Mail ( Roaring skies )
Sometimes you are just looking for one card that can win you the game. And this card will help you find that one card.
Look at the top 4 cards of your deck pick one trainer card you find there and put it into your hand.
Outro
Anyways this was my beginners to competitive Pokemon. I worked on it for a couple of days and i hope it helped
First of all decks look kinda like this 10 pokemon 10 energy 40 Trainers ( around ). You normally build a deck around just one pokemon. And there are certain pokemon that are good i will list those in the next Also there is something called format rotation. This is when cards have gotten too old and they go to a different format. In standard ( right now ) we have primal clash , Roaring skies , Ancient Origins , Breakthrough , Breakpoint , Fates collide , Stream Siege , Evolutions. In expanded we have : Black and white , Emerging Powers , Noble victories , Next Destinies , Dark Explorers , Dragons Exalted , Boundaries crossed , Plasma storm , Plasma freeze , Plasma Blast Legendary treasures , Xy base , Flashfire , Furious fists , Phantom forces , Primal clash , Roaring skies , Ancient Origins , Breakthrough , Breakpoint , Fates collide , Stream Siege , Evolutions. Expanded has more sets and I suggest starting off with it.
Decks to use
Standerd
This is where i'm not very great but i know what it is. These are four decks that are great in standerd
Mega Ray
In mega Rayquaza you deal 30x the number of pokemon you have on your bench and with the card Sky Feild you can have 8 pokemon on your bench meaning 240 damage cap.
Mega Gardy
In mega Gardevoir you discard your pokemon to deal extra damage
Greninja Break
This deck uses Greninja Breaks Ability to snipe Your opponents shaymin ex.
Valcion
This deck Uses Valcain ex abilty to power up some fire attackers like …… Vailcaion
( i'm sorry i can't spell this things name for my life )
In expanded The format is
Night march
This deck uses battle compressor to deal 180 damage or more very easily
Trev
Locks your opponents out of using items. Which pretty much wins the game ( i will explain in the next subheading thing )
Yveltal
This deck destroyed by flooding energy onto all of your Pokemon
Cards that are a virtue to every deck
In every good deck you need the cards i am about to list.
Shaymin ex ( roaring skies )
Excluding Greninja . Every deck needs to draw without using a supporter. ( as you can only use One per turn ) and SHaymins ability lets you draw cards until you have 6 in your hand.
N ( Fates collide , noble victorys )
A very game changeing card. It can be risky but it pays of more of the time
Each player Shuffles Their hand into their deck and draws cards equal to the amount of prize cards they have remaining
Professor Sycamore ( xy base , Breakpoint , Phantom forces , Steam sige )
Sometimes you are just looking for one card that can win you the game. And this card will help you find that one card.
Discard your hand and draw 7 cards
Lysandre ( Flash fire , Ancient origins )
Sometimes you need 2 more prizes to win the game. You play this card to knock out your opponents Shaymin ex
Vs seeker ( Phantom forces )
I think the description of what the card does will teach you why it's good.
Put a supporter card from your discard pile into your hand.
Acro bike ( primal clash )
Sometimes you are just looking for one card that can win you the game. And this card will help you find that one card.
Look at the top two cards of your deck put one into your hand discard the other.
Trainers Mail ( Roaring skies )
Sometimes you are just looking for one card that can win you the game. And this card will help you find that one card.
Look at the top 4 cards of your deck pick one trainer card you find there and put it into your hand.
Outro
Anyways this was my beginners to competitive Pokemon. I worked on it for a couple of days and i hope it helped