Go for a walk. Come back in half an hour and write. While you walk, have a conversation inside your head about your fic, whether you're talking to one of your characters, your imaginary friend, or even me. Discuss with them the basic premise of the story, the characters. Try to imagine them (if a character) as a real person, and think what they'd actually say, not what you want them to say. Model them off someone you know, and tweak their personality excessively until they're interesting. Then ask them questions. Start with easy things. Ask them how old they are, where they live, what their place is like, how their family situation is. Do they have a pet? Does anyone they know train Pokemon? Do they train Pokemon, or want to? Do they have any irrational fears? (like Misty and Bug-types). See, this way, you build up a character. Then even if you have nothing else to build on, you have a solid, three-dimensional character to work with.
If you can multi-task while talking to your character, look around you at the scenery. Get ideas for your setting. Ask your character whether they like the look of that house, or whether they think that girl's skirt is a little too short. This will also help build your character. Parks are good, as you get a feel for your character's relationship with nature.
I could go on like this for ages. Try it?