The Reassembly Unit is the essential block for assembling Zygarde.
When a player uses a Zygarde Cube on the Reassembly Unit, a menu will open for reassembling Zygarde. If 10 Zygarde cells and one Zygarde Core are brought to the Reassembly Unit in the Zygarde Cube then a 10% Zygarde will be formed. If 50 cells and one core are brought to the Reassembly Unit then a 50% Zygarde will be formed. And if 100 cells and two cores are brought a 50% Zygarde with the ability Power Construct will be formed.