All I can say is cool. I just hope that the Battle Tree isn't like the Battle Tower, Battle Subway or Battle Maison in other games. Its also awesome that Red and Blue are back, with a redesign. Also, Tapu Lele, Tapu Bulu and Tapu Fini are awesome with pretty cool abilities (especially Tapu Lele with the ability to set up psychic terrain which blocks priority moves against psychic types.) Their Z-move is a bit weird though, especially when you'd expect Z-moves to get strong enough to OHKO a Pokemon and the fact they have Nature's Madness which halves the Pokemon's current health.
The starters types are awesome. Not to mention they have signature moves. Decidueye's Grass/Ghost type is only slightly better than it's previous typing because it still has 5 weaknesses, but it now has one more immunity, no 4x weakness and 1 more resistance. Incineroar's (awesome name, in my opinion) typing is pretty cool in that it has 6 resistances and 1 immunity (although it has 4 weaknesses). Primarina's typing is also pretty good in that it has 6 resistances, 1 immunity and only 3 weaknesses. Moving on to signature moves, Decidueye's Spirit Shackle might be good depending on how much damage it does and what other moves it can learn (such as toxic or perish song). Incineroar's Darkest Lariat is pretty useless in terms of competitive use unless you come up against something that is boosting its defenses. Primarina's Sparkling Aria is a bit weird in that it heals the burns of any target it strikes. If it was something like Wake-up Slap and the damage was boosted when you hit a burned Pokemon and you could team it up with Scald, then maybe the ability would make sense, but since it seems that isn't the case, it's more competitively useless than Darkest Lariat.
One thing I forgot to mention is not only is Tapu Lele a great Pokemon because of its ability, it's also got a great typing, with 1 immunity and only 3 weaknesses. All that is left is to know what its stats are.
Just on a side note, I find Alolan Persian's description to be pretty funny. How anyone can find the face to be beautiful is beyond me.