Alola has a really tall Exeggutor- at over 35' tall, it usually doesn't fully fit on-screen! It trades its old Psychic sub-type for Dragon-while retaining a few Psychic moves, it gains its own signature move Dragon Hammer, which is pretty much an epic head butt.
Marowak also has an interesting new form, trading Ground for Ghost and Fire. While this breed was known for wearing its mother's skull, now it outright posses her bones! Does that mean it dies when it evolves? Either way it's pretty creepy. It has a signature move, Shadow Bone, which may reduce an opponent's Defense; it also has the new move Stomping Tantrum, which does massive damage if the user's previous attack failed or was ineffective!
Dhelmise is one that throws you off when you see it-is it Ghost? Steel? Grass? Water? It's actually Grass and Ghost, as it is the cursed seaweed that is holding the ship's wheel and anchor together, not to mention the compass/eye. It has a signature ability, Steelworker, which boosts its Steel attacks by 50%, effectively giving it a STAB.
Necrozma is a somewhat secret Pokemon-after catching all the Ultra Beasts, Looker will mention the sighting of another possible Ultra Beast, which will be found at Ten-Carat Hill. This Psychic type is pretty solid, with Prism Armor that reduces the damage of Super-Effective attacks and it shoots powerful Prismatic Lasers, so make sure you have a good Dark type in your party, especially one with False Swipe if you want to catch this beastie.
Marshadow is a myth. It is not yet attainable in the game and will likely be a future event Pokemon. This guy is an interesting Ghost and Fighting type, a cute little shadow creature with candle flames for eyes. It can use the new Laser Focus which makes its next move a critical hit, and has its signature Spectral Thief which steals a foe's stat bonuses on top of doing damage. This attack has a cool Z-Move name; Soul Stealing 7-Star Strike-it's description is pretty much Akuma's Instant Hell Murder from Street Fighter!
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