The first question I would like to ask is: what decks are you using this against? Theme decks? Modified theme decks with extra multi prize Pokemon added? League Battle Decks? Refined lists of top decks?
The second question I would like to ask is: are you playing casually with friends who aren't as experienced in the competitive side of the game, or are you looking for a fun deck you can take to your local league when you're tired of playing one of the top decks?
My final question is: Are these all cards you already own, or are you planning on buying all the cards in your final list?
As for the deck list itself, I would encourage you to pick either Garchomp ex or Tsareena ex. Justinbasil has lists for both of these decks.
https://www.justinbasil.com/new-decks/sv4#garchompex
https://www.justinbasil.com/new-decks/sv4#tsareenaex
Here are a couple of alternative lists.
https://play.limitlesstcg.com/tournament/653697ab8a7d9977b0c6927d/player/babyeatingbaby/decklist
https://play.limitlesstcg.com/tournament/65399b5b8a7d9977b0c6a1d6/player/videogamehouse/decklist
Before buying any of these decks, I would encourage you to learn more about them. If you have a set of card sleeves you can use, put 60 random cards (such as basic Energy) in them, print out the cards from one of these deck lists, cut out the images, and put them in the sleeves on top of those cards. (This called making a proxy.) Play a few casual games with friends and see if the deck works well. (Even top players do this when deciding whether or not they want to buy a deck to use it at tournaments.) If you're not satisfied with the results, you will probably want to test another deck, probably one of the top decks like Miraidon ex. Justinbasil also has a great guide on printing and using proxies (
https://www.justinbasil.com/guide/proxies) and on testing new decks in general (
https://www.justinbasil.com/guide/testing) (I just shared those two links for simplicity, but he walks players through the entire process of deck building, and you can access every stage of the tutorial here.
https://www.justinbasil.com/guide).
Hopefully this information is helpful!
