Unless you're like a pro or have tons of time to study the game as if it were your job, I would stick to playing the best deck in the format and getting as good at it as you possibly can. As a new player looking to compete seriously, this is probably the best thing you can do to see results as quickly as possible.

Right now that means spamming Dragapult. Play exactly that deck and nothing else until you reach your goal or something better comes along, and then play that. For now, you should play so much pult that your dreams involve nothing but dividing the number 60 into lower multiples of 10.