I think that certain classes of ships (nothing above destroyer) and about all the ground vehicles should have the ability to squad up. Like for aircraft it can only be up to 5 vehicles. However for the naval squadrons (i'd suggest flotillas or fleets) I think the lead ship should be a capital ship (Aircraft carrier or battleship) and the other ships are smaller vessels like destroyers or corvettes. As for ground vehicles I dont think that there should be such restriction.