Congratulations on your new budgies, they're adorable!
Are they all siblings from the same clutch?
Basing from the photos, the budgie on the first pic looks like a girl.
The grey budgie on the right is a young girl too, while the other standing next to her on the left is a boy.
The budgie on the last pic also seems to have a very pinkish coloured cere making him a boy.