That looks very like a blue hoodie with felt sewn on! I'm betting you would be able to do it ourself with a bit of patience!
>w< I have no idea how, but I just needed to say that that outfit is adorable~
Actually I can provide you with some ideas on going about creating said costume in the picture. I've created cat paws, tails, ears, and other furry type cosplays before with just a couple items. Takes a little patience, but crafting something yourself and wearing it with pride around a convention doesn't compare!
Start with a "Shell"
This is good practice for newbies. I made my cat paws out of an old pair of winter gloves rather than fabricating the entire thing from scratch. Buy a cheap blue hoodie that's thin or a light weigh blue coat with a zipper. There's hundreds of them to buy off the net, especially Amazon so you can choose the right shell of the costume you want.
Buy a bunch of Felt!
Go to your local craft store or even Wal-Mart and buy large sheets of felt of the corresponding colors of Lucario. Use a cheap crayola marker to trace the pattern in the felt and cut it out with scissors. Use multiple layers of felt to add more thickness and so it isn't see through since felt is very thin. After you've got the basic patterns for the lower half of the costume, use that hot glue gun! Hot glue is the easiest ways and secures fast. Make sure to do a zig zag pattern and along the corners of the felt to be attached so it stays in place.
Molding Ears and the Claws
I actually don't like the pics flat use of the felt fabric. Create a pattern for the ears by drawing large painted ovals. When ya get a good first one you like, use that to trace the other so you get matching ears. Glue 2 pieces of the ear pattern felt together along the corners but leave one small opening so you get a "open sandwich like bag." Buy a couple bags of cotton balls and stuff it! After that "seal" the opening with hot glue. You can attach the ears with hot glue, staples, or a simple stitch. Sewing is pretty easy after a little practice. You can do the same sort of thing with the claws!
It actually isn't too hard too construct this type of costume with a felt and shell pattern, should take about a weeks work!