like get every single zygarde off the gts and separate them
Through separating one or more outsider Zygarde, it is possible for the Zygarde Cube to hold up to 999 total Cells and Cores. Even if the Zygarde Cube has already reached this capacity, Zygarde Cells and Cores can still be collected around Alola and the Reassembly Unit can still separate Zygarde, but the number of stored Cells and Cores will not increase.
Source: https://m.bulbapedia.bulbagarden.net/wiki/Zygarde_Cube Go to the Reassembly Unit section for my answer. I hope I helped!
