>>30989514Trainer kits have 2 half decks, premade, for the purpose of learning the game. The Pikachu Libre/Suicune kit is like $12-13 and has an exclusive Pikachu Libre card, so I'd say grab that if you don't want to spend a lot.
I would honestly suggest getting the Keldeo/Rayquaza Battle Deck if/when you really want to learn some more advanced stuff, as it's 2 full 60-card decks and those in particular have a ton of super useful cards in them.
Elite trainer boxes have everything you need if you're starting out. They come with dice, energy cards, poison/burn markers, damage markers (but you're better off using dice for that), a paper playmat, and 8 boosters of whichever set that box is from.
Tins have 4 booster packs plus the EX card you see in the front.
There's more random ways they sell cards but the rest you can see what's in the box. Hope that helps.