not to battle each other!
Oh no! Ive misunderstood. What are they using the kids for?
To destroy the walls i.e. parade island. Remember that the beast titan's name is Zeke?! He is Eren's brother I believe. And all the other conscious titans (Anne, Reiner, Bertolt) are the Elodian children who were made into titans. Thats why they plan on destroying the people inside the walls. They were trained to do so. This is my theory at least.
And to collect fossil fuel. I mean hunger games held to instil fear. Mere send elodian kids to more,,,, yeah like modern war reason actually.
So theyre collecting children to battle each other and when they win, theyll be titled Warriors. So... is this The Hunger Games Arc??