Latias is highly intelligent and capable of understanding human speech. It is covered with a glass-like down. The Pokémon enfolds its body with its down and refracts light to alter its appearance.
– Pokemon Sapphire Pokedex
Latias is one of the first gendered legendary Pokemon; it’s always female, whereas its counterpart (twin, if you will) Latios is always male. Despite being gendered and there being more than one (as seen from the anime), it’s in the undiscovered egg group and cannot breed.
Latias was featured, along with Latios, in the 5th movie, where we saw a sister-brother pair of Latias and Latios, and there was mention of a father Latios. I guess it can somehow reproduce in the wild, but not by trainers, haha. In the movie, Latias was seen to understand human speech, and be able to transform herself to look like a human. Unlike Lugia and Mewtwo who were able to speak human speech telepathically though, Latias could not speak.
Latias’ type of Dragon/Psychic is unique to her and Latios. It’s not a great type combination though, as neither type covers the weakness of the other. She has the ability Levitate because she looks like a plane and is seen flying. I think she could pass for Dragon/Flying or Psychic/Flying, because her design is quite bird-like. In fact, her Pokedex entry says she’s covered with down (even though you can’t see that at all from the sprites, official art, or the movie/anime).
Stat-wise, Latias has high Sp Defense, the highest of all Dragon types, and good Sp Attack and Speed. Her signature move Mist Ball has 70 power and 100 accuracy, and 50% chance to lower target’s Sp Attack, a pretty good Psychic move. It has lower power than Psychic, but the secondary effect can come in handy. Latias’ level-up moveset consists of a lot of Status moves, combined with her high Sp Defense and passable Defense, she could be used as a good defensive supporting Pokemon; but she has good offensive stats and moves as well.