Balcephalon-GX could be Psychic (most likely). Depending on whether it’s ability is good or not determines if Beast Box will play it.
It’d make a lot of sense for Lugia-GX to be Psychic (though it may just end up being Colorless again, with Lightning Weakness). Looking at past Lugias, this one could have any of the following:
• a defensive or Energy-accelerating Ability
• an attack that accelerates Energy
• a powerful attack that requires discards (which could pair with Malamar)
• worst possible Lugia, one that requires more than 1 type of Energy for attacks
No idea what the GX attack would be, and maybe Lugia could be something totally different.
Tyranitar-GX is gonna be Darkness, and a Stage 2 Darkness would suck, sorry.
Based on past cards, Tyrantiar could have an attack or even an Ability (which would be great) that deals a little spread damage.
We’ve seen Zeraora-GX and we already know it’s a stupid good card.
We’ve also seen Ditto Prism star and I can guess it’ll be useful in Zoroark variants.
Celebi Prism Star could be anything.
Based on past cards, it could have an Ability that saves it from being KOed and sent to discard (like Neo, Celebi Star, or XY93), which would make it pretty good as it could save itself from a Lost Zone fate.