Five Decks I'm Trying Day One of Triumphant Light

Dialga EX got two support pieces the archetype was sorely missing. Shaymin provides a toolbox-style retreat aid, which can lessen the burden on finding Leaf to pivot out of your namesake ramping metal dinosaur. Arceus EX gives an actual Basic attacking threat that caps out higher than Heatran without the self-damage downside.

The exact supporter count is still in the air, but I'm leaning towards the 2x Leaf anyway just to ensure the maximum ability to pivot to whoever my primary attacker ends up being. It could be that the second copy of Dawn finds its way back into the deck to more consistently enable Heavy Impact on Dialga EX's second attack. Giovanni feels like a requirement in order to shift Arceus EX's damage breakpoints to hit more one-shot KO's easier.

We still don't have an attacker that can attack before our second attacking turn, so be careful of being tempo'd out of the game before you get a chance to get the ramp rolling.

Alternative options: Origin-Dialga/Heatran/Adaman package, Probopass EX, Bronzong

Sadly, "baby" Arceus is unplayable trash, meaning in order to enable Carnivine's Power Link ability, we need to risk 2 points. Thankfully, Arceus EX is a totally servicable attacker, and we can play effectively a variant of the popular Skarmory/Magnezone aggressive deck that has a different setup condition. The reason I'm intrigued by Carnivine is the ability to two-hit KO Darkrai EX and Weavile EX thanks to hitting for weakness, which Skarmory cannot manage. Pokemon Communication is doubly required, as we need to hit our Carnivine/Arceus EX "combo" but we also want to find our Stage 2 line as soon as possible.

Alternative options: STS Leafeon + Erika over the Magnezone line, X Speed

The main advantage Crobat and Arceus EX can claim over Magnezone variants is pure damage potential. Cunning Link + Nightmare Aura + a full bench Ultimate Force threatens a massive 180 damage in one turn, easily muscling through even Charizard EX and a caped Exeggutor EX. Similarly to the Power Link deck, 2 copies of Pokemon Communication is a hard requirement.

As we want to be attacking with Arceus EX at some point, we also find room for 2 copies of Dawn in order to get value off of Nightmare Aura. The Golbat you choose is personal preference - I'm electing for the 40 damage over the 80 HP in order to maximize the value we can get for attacking on curve going first.

Alternative options: Retreat utility, Giovanni, Giant Cape

Now we get into a bit of spice! Triumphant Light Staraptor is an intriguing option in place of Magnezone and Greninja as the Stage 2 of choice to accompany Darkrai EX for, again, sheer damage output. Staraptor's Brave Bird clocks in at a frankly absurd 130 damage with the downside of sustaining some self-damage, but in exchange we can attack for the low cost of just one energy thanks to Barry. We use two copies of Dawn to, again, gain some value off of the energy that had been committed to our Darkrai EX once we need to start attacking for the actual printed cost on Staraptor.

Alternative options: Retreat tech, an additional attacking Basic

"MKCrimson, you can't just put Arceus EX and Darkrai EX in all five decks!" Well, this is the best I've got with what the set is giving me. Croagunk from the new set, believe it or not, gives a pretty massive boost to STS Toxicroak as it can actually attack on turn one. Our two copies of Team Galactic Grunt give us a ton of consistency in finding our Basics so we can attempt a Group Beatdown as quickly as possible. A full-field Group Beatdown has an expected value of 60 damage, but can easily highroll to 120, smashing through the vast majority of earlygame tanks. Glameow and Farfetch'd give us as much early damage as we can squeeze out. We either win fast or flame out, so we run a suite of 2 Sabrina + 2 Cyrus + 2 Giovanni for maximum tempo. Go fast or go home!

Alternative options: Darkrai EX (I can't help it, I'm sorry!)