It seems necessary to follow the Weight Chart with a Tea-Cup statement.
A teacup is something to drink out of, a chihuahua is a very small dog. Don't get them mixed up! There is no standard calling for Tea-Cup, Toy, Miniature, or Micro Chihuahuas. Please don't ask me for one. These terms are used very loosely, and are usually used to overprice an otherwise normal little dog.
If you are interested in a very tiny chihuahua, please feel free to contact me, and we can discuss the pro's and con's of the very tiny pet. You are welcome to come see my dogs, and hold them, and see how small a 5 lb dog is, and learn how much healthier he is than the 2 lb pet you might be wishing for....