Oh gods! This batch of cards are all very meta relevant.
Blaziken-GX
Blaziken-GX synergizes beautifully with the Firestarter Blaziken. Explosive Flames is hitting that goldilocks-number with 210, which means it won't have to worry about Choice Band most of the time unless fighting other Stage 2 GXs. The first attack is meh and so is the GX attack, but I have seen people suggesting another partner for Blaziken-GX with a GX attack that you would be more inclined to use: Ho-Oh-GX
Ho-Oh-GX is a good attacker in the early game along with Kiawe, which give you some time to set-up your Firestarter Blaziken. And then, rather than evolving manually, you place the Blaziken-GXs in play with Eternal Flame GX. Though, would it work well enough? Perhaps or perhaps not.
Altaria-GX
I did not expect an Altaria-GX in this set, nor did I expect it to be frighteningly good. It basically has the same game plan as Zygarde-GX, but is much less resource heavy. And Altaria-GX is positively swimming in the Dragon support that there will be after rotation. It goes without saying that Altaria-GX goes well with the Fight Song Altaria, which makes Bright Tone go from a 3HKO move to a 2HKO move with 2 Fight Song and a Choice Band (hitting for 120). And considering the immunity Bright Song provides, Altaria-GX can definitely afford the slower KOs.
Lance ◇ also works beautifully with Altaria-GX, which allows you to get more Altaria in play than you could evolve from Swablu. This is what I would say what makes Altaria-GX go from being an interesting card, to an excellent card. Lance ◇ gives you more options, you don't have to worry as much as to what mix of Altaria-GX and Fight Song Altaria you will have to play.
Latios ◇
After Victini ◇, I was hoping to see more offensive oriented Prism Star pokémon rather than mainly supportive. And Latios ◇ is definitely that. All I can say is that Victini ◇ wished it had an attack as good as Dragon Fleet. This attack is a game ender in decks like Dragonite-GX and Altaria-GX. Both of those decks mainly focuses on 2HKOs (at least most of the theory builds of Dragonite-GX I've seen do), so suddenly being able to shift up the tempo with Latios ◇ will be huge. With two Fight Song Altaria around and a Choice Band, you can hit for huge numbers even with just one other Dragon-type Evolution card in play (220 damage).
Make no mistake, this a must-have in any Evolution-based Dragon-type deck.
Steven’s Decision
With N and Brigette gone, this will be the turn 1 Supporter. It is a perfect set-up supporter if it doesn't get checked. It will also force the opponent to either play a Judge to check Steven’s Decision, but also risking hurting their own hand and set-up, or leave to opponent's hand be, to play their own Steven’s Decision. At least I reckon this will get a lot of play, at least as a one-of.
Lisia
Lisia might be the least 'flashy' card of this bunch, but as we see more Prism Star cards, the more relevant Lisia becomes. We already have Buzzwole-GX who very much would appreciate having Lisia already, and as I described above, decks running Latios ◇ and Lance ◇ would also like Lisia. I think Lisia will be an interesting tech card for decks that run more than 1 Prism Star card.