Jirachi will awaken from its sleep of a thousand years if you sing to it in a voice of purity. It is said to make true any wish that people desire. It is said to have the ability to grant any wish for just one week every thousand years. Generations have believed that any wish written on a note on its head will come true when it awakens.
Pokédex entry #385
Jirachi is a type psychic and steel Pokémon that doesn't evolve
Jirachi in Pokémon GO
It's possible to hatch Jirachi from an egg?
No, Jirachi can't be hatched.
Which are Jirachi’s strengths and weaknesses?
Jirachi is a psychic and steel type Pokémon. psychic type pokémons are strong against fighting, poison, ghost pokémons but weak against bug, shadow pokémons. steel type pokémons are strong against ice, rock, fairy pokémons but weak against fire, ground, flying pokémons.