The Psychic/Dragon-Type Pokémon . While Mega Latios isn't the best Mega out there, its solid strength and balance for both Psychic and Dragon damage make it a great option.

With Snorlax, for example, we learn it takes the most damage from psychic-type Alakazam using Psychic or Psycho Cut, and it takes the least damage from Chansey using Zen Headbutt, ...

They're so much more than just spots on Bill's PC. Despite the fact that it isn't classed as a Psychic type, Noctowl actually learns more Psychic type moves than it does Flying type.