My daughter went to a pokemon tour day last year and happened to tell me two weeks in advance she still needed a costume.
Should I be flattered or bursting in anger? TWO WEEKS! No pattern, no fabric and naturally not the slightest idea who this Raichu may be. Well, the last was fixed by my daughter, telling me over and over it's the last evolved stage of Pikachu.
She went together with a friend of hers being Pikachu - and hey, they won fourth place having about 60 competitors! Seems I did *something* right.
I'll stop talking now and give you the pics:
Front. She's looking through the mouth - I sewed black tulle in two layers into it. She had quite a good view and could breathe easily this way. Me personally, I hate it when you start breathing your own warm, wet exhalations. Yuck.
Back - I fixed the tail with nylon cord and a safety pin so it could swing but not be stepped upon.
Everybody absolutely LOVED her! Wherever she went, people cuddled her and wanted to take pics.
Absolutely able to compete, isn't it? She could have been a little more stuffed up, but I remember the faces of the actors wearing the original costumes - they were all puffy and sweaty, even on this not-so-warm-day. My daughters belly just holds it form due to wires and reeds - no extra stuffing (and she's a thin little fishy).
Oh, and I made the hands with a slit to get your own fingers out to handle something. For further convenience (especially bathrooms) I made the costume being three parts: trousers, body with crotch closure, head. Everything is stiffened up with wires and/or reeds (like the ones you use for baskets), the legs are stuffed with styrofoam(?) like you find in cheap pillows.
Hope you enjoy,