>>54017872-- a stock deck generally runs 15 mons, 35 trainers (of which 11 supporters and 1-3 stadiums), and 10 energies.
-- mons that draw cards are very important, currently the 2 main ways to go about it are a 2-2 line of industrious incisors Bibarel or a 3-3 line of refinement Kirlia
-- You have too many attackers, decks generally run 1 main attacker and 1 alt attacker
-- Toxicroak is nice in that you can run both the ex and a small one for different scenarios, and can use double turbo energy
-- Slowking is nice in that it has more hp and access so single strike cards like houndoom for easy energy.
-- since the strength of the deck is damage over time, you can try preventing your opponent from switching, with Spidops ex and calamitous wasteland
-- for supporters, prof research, boss's order, and Iono are staples that should be run in some numbers in most decks
-- basic "draw 3" like Nemona are just plain bad since strictly better version exist in Avery, Miriam, etc.
-- ways to seach out mons are very important, so youy should at the very list play the full 4 nest and hyper ball
-- look up the pastebin, justinbasil for deckbuilding guides, and limitless for deck ideas. Add to that pokecabook for japanese decks.
Pic related I tried making a competitive Toxicroak-Spidops deck, haven't tested it though, so can't guarantee anything.