Welcome to the game, Scooby!
Before you get into deck building, you should definitely check out the
most recent rulebook so you can get a full understanding of the game. Once you understand how the game works, you should decide how competitive you'd like to play. Are you planning to attend (and win!) tournaments? Or are you just wanting to play casually with friends? Unfortunately for Charizard or Pikachu (or Raichu) decks, the cards are not highly tiered in the competitive scene, but the more decent card combos are
Mega Charizard-EX,
Pikachu-EX/
Magnezone BKP and
Raichu XY. (The Pikachu/Raichu variants are actually better than Charizard-EX.) If you're looking at playing competitively, you should know that there are these things called "formats". Currently, there are two - "Standard" and "Expanded". Due to the vast number of expansions printed in the PTCG, these formats narrow the cards that can be used in competitive play to the most recent expansions. They also rotate at set time each year, as more expansions are printed. In a few months, the format rotation will change for 2017 to be Black and White-on for Expanded and Primal Clash-on for Standard.
As for deck-building in general, my best recommendation would be to put the effort in and get familiar with well-performing decks - compare and contrast what is commonly used, and think about why! You can find some metagame deck skeletons
here, check out the
Deck Garage for PB community decklists (you can post your complete decklists there too, for feedback!), read some PB
front-page articles, or check out top-performing decks of the
recent Nationals Tournament.
This front-page article documents the writer's thought processes in creating his Serperior deck, and
this article from the
official Pokemon site gives some tips on making cheaper (EX-less) decks. It's best to get involved with the community and ask questions so you could broaden your knowledge on the game. You can do this both in real life or on the forums here! If you're looking at competitive play, finding a league would be a great option. Finally, it may be worth checking out the
official PTCG emulator, which is great at teaching new players the game and getting them started off with deck building, without needing to spend money.
Anyways, good luck, and if you have any more questions, feel free to ask!
