Information on the box-art legendaries
Solgaleo is Sun's mascot. He is Psychic/Steel, the same two types as Jirachi, and Bronzor/Bronzong. He has a new ability called "Full Metal Body" which has the same effect as "Clear Body" and "White Smoke", i.e. the Pokemon's stats cannot be lowered by its opponent's moves or ability. Solgaleo also has a signature move called "Sunsteel Strike", which ignores its target's ability -- i.e. the move effectively has its own Mold Breaker effect.
Lunala is Moon's mascot. He is Psychic/Ghost, like Hoopa. He has a new ability called "Shadow Shield", which allows it to take less damage from a hit if it was at full HP, in other words the same effect as "Multiscale". Lunala has a signature attack called "Moongeist Beam" which ignores the target's ability just as Solgaleo's signature move does.
More information on the region, the professor, a couple of characters, and such can be found here. Player character pics included.
http://bulbanews.bulbagarden.net/wiki/Pok%C3%A9mon_Sun_and_Moon_box_mascots,_characters_detailed
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I am disappointed by these, overall. I was hoping for originality in the legendary typings, but no. Their abilities, while new, are just clones of ones that already existed. A signature move with the effect of Mold Breaker is kind of cool, I guess, but that they both had to get one is just ... bleh.
Solgaleo's typing gives it four weaknesses (Fire, Ground, Ghost, Dark). It has nine resistances plus a Poison immunity, so if it has a good amount of bulk it could be threatening.
Lunala's typing is just bad though. Only two weaknesses, but both are doubled, with Ghost and Dark being bad types to take quadruple damage from. It is immune to Normal and Fighting, which is nice, but it only has two resistances, to Poison and Psychic. I foresee its competitive viability taking a big hit from that typing.