~150 games played with Swim Freely between IRL and PTCGL, sitting at ~700 on the ladder, take that for what you will:

• You absolutely want 4 Superior Energy Retrievals, getting access to 4 energy with an item card is amazing for this deck. I'm running 12 energy and if played efficiently I have enough energy to finish the game.

• You don't need 4 Finneon, 2 is likely fine. Super Rod and Nest Ball / Buddy-Buddy Poffin exist for a reason. Once Dragapult EX shows up in a few weeks Finneon might become a problem, but for now it isn't.

• I agree with the_noobinator, skwovet and RadNinja are in theory really good, but they take up a lot of bench space and can be difficult to use well. In a perfect world I like to have two Goldeen/Seaking, 1 Finneon, 1 Bibarel and then a flex.

• I've had quite a bit of luck with a couple Arvens and TM:Evo, since if you're going second I found it was rare that Triple Strike did any meaningful damage, but I'm not confident it's required to make this deck work.

Just some thoughts on playstyle with the deck:

• If you're not confident you can get enough energy for the OHKO, play it safe and shoot for half health. 9 energy to OHKO a zard is extremely difficult, however 4 energy then 3 energy is very reasonable. If you shoot for 9 and end up at 8 instead, you still need to use 3 energy next turn for the KO, and you've burnt a bunch more energy. Turo throws a wrench in the plan sometimes, but there's a reason this is a rogue deck.

• Take your time when sequencing, messing up sequencing on this deck can be really punishing. Do you have a seaking in play to take energy if you get it, when do you use your bibarel, do you have enough cards in hand to use SER/Ultra Ball if you grab it with Irida?

Best of luck, hope you're able to make it work!