>>34870831Dawn Wings Necrozma looks way better than Lunala. Bats look cooler wearing Batman's costume.
>>34871443Dialga's design is fine and makes it look more like a counterpart to Groudon than Kyogre. They're both dinosaur-like, while Kyogre is some prehistorical killer whale that looks like it lived long after Groudon.
Pokemon's designs are hit or miss but the worst tends to be when they're overdesigned. Most Megas are like this, except the ones that look like legit 4th evos (Gardevoir, Mawile, Banette, Sableye).
Necrozma suffers from this because GameFreak tried to make it look scary. A legendary/Ultra Beast who Mega Evolves but still has a Z-Move! The chicken look is most apparent in the sprite, the concept art looks more draconian, but it still looks really frail (and actually is easy to revenge kill).