Plated is subjective for the following reason: Different brands use different levels of plating thickness and different levels of core hardness from nearly dead soft lead to BH12 alloys. I found that Rainier tend to use soft alloy cores and thin plating. If you look at Accurate Arms load data, they have loads listed for Rainier plated and the charge levels are usually less then that of lead bullets. Xtreme (formerly West Coast then Accura) use hard alloy cores and thick plating. I have driven their 158 gr. semi wadcutter 357 bullets to near top W296 load data without stripping the plate and still had good accuracy. I have driven their 110 gr. 30 carbine bullet to full throttle and couldn't tell the difference between it and other major manufacturers FMJ's; I have shot 5k of these over the years. On the far end of the scale are Speer Gold Dots and Uni Core bullets. These have the thickest jackets but also use varying hardnesses of core depending on the application. YES The Gold Dot is a Plated bullet!
That said, each brand is a law unto itself. The one thing you need to be careful of with some brands is applying too much crimp. The next thing is to know what the velocity limits are of the brand. The manufacturers are usually quite up front with this info if you ask for it.
This is based on close to 20 years of experience using plated bullets.