Spoilers!
In Chapter 7 Episode 2 we followed Emma Berry as she stumbled into a strange, alien facility far, far away from home. Short story shorter: it's a cloning facility and soon she'll be producing copies of herself in huge numbers. The cloning vats even allow for various sizes, ranging from 1/100th the size of the original up to 10k the size (in steps of 10)!
The big Emmas serve as heavy fire support and to transport the "little" ones. They actually have no trouble carrying dozens of Emmas into battle and with a backpack, they can carry even more! In return, the Emmas in their pockets can provide fire support and if standing on their shoulders can function as spotters and communicators.
Disclaimer: The story, all names, characters, and incidents portrayed in this production are fictitious. No identification with actual persons (living or deceased), places, buildings, and products is intended or should be inferred.