From Bulbapedia, the community-driven Pokémon encyclopedia.
If you know exactly what you need information on, it's easy to find it on Bulbapedia: Enter the name in the search box on the left menu, and hit Go. In many instances, this will take you to the article you're looking for, since there are redirects of common name variants leading to the right article.
Sometimes, you might hit a disambiguation page. In several instances, different articles will have the same name. For example, Red can refer to a game, a character in the games, or a character in the manga. Psychic can refer to the type, the move, or Psychic, all of which can be found in the same games. These disambiguation pages can be a little annoying, but they will help you rind the right subject as quickly as possible.