Welp, here's what I think of these cards so far.
Solgaleo-GX - Sol Burst is definitely interesting, but it seems like it could be ruined by Lysandre if the opponent can KO what you powered up. Sunsteel Strike is just another "all-in" attack that'll likely cost too much Energy to be worth it (though I have to admit, it is powerful).
But then there's Ultra Road, which I think is completely and totally broken. We all know the real reason why Lysandre's Trump Card was banned (it made Mega Ray and Toad the only viable decks when Roaring Skies came out), but one of the reasons the Pokémon mouthpieces gave was that it invalidated decking out as a factor. Ultra Road invalidates so much more than that, it's not even funny: Sleep, Paralysis, Special Conditions in general, opponent's-turn attack effects in general, and even Retreat Costs, all from this big Basic Solgaleo just existing on your field (it doesn't need a Float Stone or anything!). Trust me, every deck that doesn't run Garbodor will run at least one Solgaleo-GX just because of Ultra Road.
Lunala-GX - Obviously, the big talking point of this card is Lunar Fall, which instantly KOs any non-GX Basic on your opponent's field. In an EX-heavy format like this, that attack will be used, even if its Energy cost is ridiculous. Thank goodness it can only be used once per game. Phantom Ray doesn't interest me that much, especially since Solgaleo makes the no-healing effect irrelevant (I'm pretty sure it'll go away when the affected 'mon is Benched, like most attack effects).
Once again, the thing that interests me the most here is the Ability, Psychic Transfer; what we have here is a big Basic Aromatisse for Psychic-types, and that's no joke at all. Max Elixir can quickly get a good amount of Psychic Energy on board, Rainbow Energy still exists in the format, and so does Max Potion. One card I can think of right away that'll benefit from this is Mega Mewtwo-EX (specifically, the Y version). It's not flat-out broken like Ultra Road, but make no mistake, this Ability is really good.