A straightforward list for Chien-Pao ex with Baxcalibur, updated for Obsidian Flames.The most notable additions are the 2-2 Pidgeot ex line, which help grab specific pieces from the deck to set up or to complete combos (e.g., gust Manaphy + Cancelling Cologne + Moonlight Shuriken). I am opting for Palkia VSTAR instead of Arceus VSTAR--ideally, Pidgeot ex will provide the consistency boost that Arceus's Star Birth would, allowing us to play Palkia instead. Palkia gives you some burst potential, is generally a better attacker than Arceus, and makes you more resillient to your only Baxcalibur being KO'd. That said, Arceus could still be better since Pidgeot seems like it doesn't help get your initial setup as much as Arceus does. It would be a good idea to test both. I'm trying a 1-1 Bibarel line in addition to Pidgeot to make the deck more resilient to Path + Iono/Judge.
This list was originally posted at the beginning of the Paldea Evolved format, but I've updated for Obsidian Flames since it's still getting views. The original writeup from Paldea Evolved is below.
The main game plan of this deck is to take big Knockouts using Chien-Pao ex, whose attack does 60 damage for each Water energy you discard from your Pokemon. Chien-Pao can hit high numbers thanks to Baxcalibur's Super Cold Ability, which allows you to attach as many Water energies from your hand as you like. Chien-Pao's ability fetches 2 Water energy when it's in the Active spot, which synergizes nicely with Baxcalibur's acceleration. Palkia VSTAR provides some burst potential with its Star Portal Ability, while also seving as a low-cost attacker.
Against Gardevoir and Lost Box, our most important attacker is probably Radiant Greninja. Ideally, we'd like to use Moonlight Shuriken to KO 2 Comfey or 2 Ralts/Kirlia on our second turn. While we can power up the frog using Baxcalibur, Palkia's Star Portal is also a great option for doing so if we can't set up a Bax. Of course, even if we do set up, Manaphy means that won't always be feasible. For that reason, this list plays 1 Cancelling Cologne.