There is not a requirement to be dressed up as a teenager. Many adults of all ages shop at stores like Hollister and Forever 21, which provide "teenager-like" clothes of all current fashions.
You should at least be a teenager and still not too much, you will look like a tramp.
I would suggest a dress but not too long and not too short maybe like the wedding dress that Nicole had in pink panther twobut it really depends if the girl like dressing up or would rather go in in a t-shirt and a pair of jeans
So if you want to be teenager you have to be 13 years old up.
To a fancy dress party? yes.
They can dress up as Alice in wonderland but they can have their own way of wearing it, Fairy but make it look like what a teenager would wear, a disco girl and a princess.
if you want to dress up like lady gaga , nothing is too... "out there"
Barbie.com
Five year old girls like to feel like they are a "big girl." Dress up clothes and simple make up (chopstick) would be an appropriate gift. Disney princesses are a huge deal with this age too. Try buying some Disney princess dolls, dress up clothes, or coloring pages.
girlgames4u.com its the best there are dress up games but not as girly as others you could possibly try GOOGLE
nope
A little black dress is always useful. The dress should not be overly dressy and not too casual either. It can be dressed up or down, and should have classic lines.
You can dress as an old woman or as Olive Oyl. You could dress as Ozzy Osbourne or as an operating room orderly.