Hey there, glad to see more people cosplaying from Pokemon!
First thing I have to tell you if this is your first time sewing, the best thing to do is to work from a pattern. Trying to go off with out one usually doesn't end well. Try to find someone that has sewn before to help you alter the patterns you pick out too, because trailing off of the directions can be confusing too.
For the cape you'll have to get a heavier fabric (I think I usually get broadcloth when I make capes) so it falls the way you want. Trying to use a lighter fabric like cotton will just flop everywhere and look bad, not to mention wrinkle like a bitch. And remember to get some lining for your cape to get that inside color as well. Capes may seem like they're big and confusing, but they're actually really easy, so don't get discouraged.
You'll probably have to make the shirt and the hat as well. I'd give you some advice but just reading over what I typed I realized it was very confusing. Just remember to use a pattern as a base and alter what you need to.
For the pants you can probably just buy some white ones and dye them that color. You can get this stuff called RIT dye at Jo-Ann's that you just throw in the washer with what you want dyed.
If you are really lost though, just bring a picture of what you want to make to any fabric store and the employees there are sure to help you out. Most of the older ones have been sewing a lot longer then anyone on this forum and are very knowledgeable. Also if you do want to try to translate my sewing jibberish for the shirt and hat, just send me a pm. I'll even draw out it out in ms paint so it's a little easier to understand. Though I'm sure someone in here will be able to help you out more then I can.
Good luck with your costume!
and if you want to try to get through my sewing jibberish and have me draw out examples if you get stuck just send me a pm.
