Veluza Water Turbo

Add 4 Irida. If this is not meant for LIVE expanded, use Octillery as draw instead. Try adding Candice if you want. If you wanted to make it standard use Baxcalibur instead of Frosmoth, replace Capacious Bucket with Earthen Vessel, and drop Aqua Patch. You should add 2 more Superior Energy Retrieval since you are loading tons of energy onto Veluza.

Tangent What should I swap out?

Articuno isn't very good so I'd swap out one or both. I'd also drop 2 Nest Ball. 4 Professor's Research is also a lot, so I'd drop 2-4. I'd also swap 2 Iono for Boss. 2 Ultra Ball should go to Switch. I'd swap Beach Court for Air Balloon so you have better pivots. In that case Arven could also be good. It depends on what you like playing with. Your main concern is pivots and adding Irida, so swap for those first. The exact swaps are flexible and what I say isn't necessarily best. Given that Aqua Patch has the same benched restriction as Frosmoth, Aqua Patch isn't even good. You could replaced it for cards like Energy Retrieval. Also Ordinary Rod is better than Super Rod except in rare cases. I'm assuming this is for LIVE expanded, otherwise I'd be mentioning Dive Ball and Splash Energy. Also a Level Ball could help find Frosmoth. If you have spare room, you should seriously consider Path.

Tangent This isn't actually for Live Expanded, it's just a kitchen table deck. Thanks for the advice!

In that case I'd suggest using Octillery (BREAKthrough) instead of Bibarel. My suggestions are as follows:

-4 Professor's Research, -2 Beach Court, -4 Battle VIP Pass, -2 Ultra Ball -2 Bidoof, -2 Bibarel, -2 Basic Water Energy, -1 Nest Ball; +2 Air Balloon, +1 Arven, + 4 Level Ball, +1 Radiant Greninja, +1 Splash Energy +2 Candice, +1 Capacious Bucket/Professor's Letter, +2 Staryu, +2 Starmie (Evolutions), +1 Nessa, +2 Brooklet Hill.

I forgot to mention that Switch Raft is better than Switch, but they both work. It would be beneficial to squeeze a Chien-Pao ex in as well if possible, but it doesn't really matter. Rescue Carrier could also be helpful. Starmie could be replaced with cards to recover energy from the discard. Remember that what I say is not necessarily what is best for your deck and your play style. Also if you have any questions about my suggestions, please let me know. you should also drop the last Nest Ball in favor of a Chien-Pao ex or a Pokémon recovery card like Nessa or Rescue Carrier.

Tangent Thank you for the help!

I'm sorry I forgot to suggest adding Octillery (BREAKthrough). This deck falls apart without draw. I had that comment get reset multiple times so I must've forgot about it. You should drop the Arven, a Superior Energy Retrieval, the Splash Energy, and Nest Ball, or another combo of 4 cards to make space for a 2-2 line. I completely forgot about draw when I wrote that comment my apologies. Float Stone is better than Air Balloon and can help against abilities that add retreat cost to your Pokémon, but it isn't a huge deal. You could also drop one. If you struggle against bench attacks, try adding a Manaphy (not Mew or Mr. Mine because Dive Ball and Irida searchable).

Tangent Thanks!

You're welcome! Here's some food for thought:

Guzma is better than Boss's Orders because you can only attach to bench with Frosmoth. A Manaphy can help if you are scared of damage spread decks like Alolan Raichu or cards like Radiant Greninja. You could also consider some VS Seeker in order to reuse Guzma and Irida if needed, but it isn't super needed.

Keep in mind that Radiant Greninja is a valuable attacker in order to take down multiple smaller Pokémon in one shot or Pokémon with leftover HP after a Hydro Pump. You can easily power it up with Fillet Memento depending on your opponent's board.
Scramble Switch would be a valuable ACE SPEC to make use of Fillet Memento and to consolidate Water Energy. It's the best ACE SPEC for the deck, unless you want to use Prime Catcher (not out yet) as an Item Guzma. Scramble Switch would be another switching card and can help with a mediocre Fillet Memento or a surprise Moonlight Shurikan. If you can't spring for one, it isn't super needed.

This is just some ideas if you want to mix up your deck and add some more options, my only suggestion is to swap Boss with Guzma. Have fun! :)

Tangent I almost forgot about Guzma, and Scramble Switch is pretty smart. I'll swap out the Boss for Guzma and one Switch for Scramble Switch. I'll do my best to remember to use Radiant Greninja when needed.

This deck looks like it has been pushed to its limit! Well done! Now all that remains is to playtest to get a solid strategy and practice. I did a few test hands, and it looks like it's pretty easy to get a solid starting setup and then is super consistent once you get your evolutions in play. I should try this deck! It was nice collaborating with you on this deck! Have fun!

Tangent To be completely honest I'm probably not gonna end up building this deck IRL since I'm a little lacking in space for cards right now, but it'll be a fun one to revisit in the future when more cards are released. Thanks for your help!