Different manufacturers will say different things about anti-seize. A quick Google search makes it looks like NGK says no anti-seize, but plenty of us, including myself, do it. The last thing I'd ever want to do is to strip out the threads in the aluminum head because the spark plug seized in the hole.
NG 900 Trionic 5 and all Motronic iterations; OG 9-3 Trionic 5 and all Motronic - refit plugs in reverse order. No mention of anti-seize.
OG 9-3 Trionic 7 (9400) - apply Molykote 1000 or equivalent (part no. 30 20 971) to the spark plug threads.
OG 9-5 Trionic 7 four cylinder (9600) - coat the spark plug threads with 90 513 210 universal paste or equivalent; OG 9-5 Trionic 7 V-6 - apply Molykote 1000 or equivalent (part no. 30 20 971) to the spark plug threads.
NG 9-3 four and six cylinder petrol (9440) - no mention of anti-seize;
NG 9-5 4 and 6 cylinder (9650) - no mention of anti-seize.
anti seize is not called for. The issue with anti seize is the material and the carrier in it. Molydenum is not a good fit for a spark plug thread I use Lloyds Moly anti seize as it very good to combat corrosion on brake pins, pad backing plates and bolts everywhere. BUT NEVER on spark plug threads. I do not use it myself on spark plugs, where I am confident of the maintennce schedule. BUT I do use, on some customer cars, Permatex anti seize, the silver stuff. The carrier is naptha and the material in it is aluminum; that works well on sparkplug threads.
The reason I use it on some customer cars, with the LSJ/LK9 and other ecotecs, is that some folks just don't look after their cars. Some don't drive them in winter but store them outside. So I get cars like that with water filling the sparkplug cavity, and it is possible for water to immerse the plugs right up to the coil pack boots. So over time with heating and cooling the moisture can wick down the threads....bad news. Permatex helps in this situation. No water would be best, however. I also torque spark plugs to 15 ft lbs, but its important if the OEM plug has a gasket , to tighten to compress the gasket, then loosen and retorque...