I would risk my life in saying that everyone who is registered here has been aware of this fact for, at least, the last 15 years. Saying this should be the same as telling someone if they know Pokémon are pocket monsters. Thank you for the information, altho i'd have just take a look at my rack where I've the original japanese green, red, blue and yellow, which, btw, don't worry, I'm also aware they are different form the ones that released later in the US. No need to take Bulbapedia further.
Lugia is predominantly White, not blue. Compare this:
View attachment 463720
With this
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Yveltal and Xerneas, alongside X and Y, are a direct tribute to Red and Blue themselves, that's the reason why Zygarde is also green and the reason why the 3 legendaries share predominant colours with the weather trio from Hoenn, and Zamazenta and Zacian are the same Pokémon with minor differences in their held item form.
Every single generation of Pokémon has been divided in cold and warm colours, usually bluish and red/pink, but not in each one those colors have been similarly predominant. Diamond and Pearl aren't as Blue and Red as the originals Blue and Red, for example (pearl is pink btw). Sun and Moon is more of an Orange Purple combo.
In fact, the color red isn't even in Pokémon Pearl box art, and Diamond has a very strong mixture of blue with black. The only editions in the history of the franchise that share the same strong blue and red as an almost monocrome box art and legendaries are Ruby and Sapphire. There's a clear difference, we shouldn't even be discussing this when it's demostrable by just watching it.