Main series Pokémon games which come in pairs can generally be divided in two categories: one version of the pair is "red" and the other is "blue". For most of the game pairs, it is quite clear which is red and which is blue. But it is not quite that clear for B/W. From what I have seen in the fandom, most people seem to consider Black as red and White as blue. But I personally prefer to see it the other way around, Black as blue and White as red. I think this is unpopular since I don't think I have seen anyone else seeing it the same way. There are two reasons for as for why I see it this way. The first is that there is actually a very minor detail on the game covers which features red and blue: Reshiram has blue eyes, while Zekrom has red eyes. I also think it makes more sense to see it this way because of the sequels. Black 2 is definitely blue while White 2 is definitely red.
While I don't think it really matters, if you want to label the games as the "Red Version" and "Blue Version" you could use the recent Legendary Hunts which has the mascots be version exclusives:
ORAS:
OR: Ho-Oh, Groudon, Palkia, Reshiram
AS: Lugia, Kyogre, Dialga, Zekrom
USUM:
US: Ho-Oh, Groudon, Dialga, Reshiram, Xerneas, Solgaleo
UM: Lugia, Kyogre, Palkia, Zekrom, Yveltal, Lunala
SwSd:
Sw: Ho-Oh, Groudon, Dialga, Reshiram, Xerneas, Solgaleo, Zacian
Sd: Lugia, Kyogre, Palkia, Zekrom, Yveltal, Lunala, Zamazenta
BONUS: In Pokemon Battle Revolution, the final boss Mysterial would use different Pokemon depending on the game cartridge you have linked:
Diamond/SoulSilver: Lugia, Kyogre, Palkia
Pearl/HeartGold: Ho-Oh, Groudon, Dialga
Going by these, and counting out the exceptions, we come to the non-surprising pattern that "Red Version" and "Blue Version" usually follows the "Version 1" and "Version 2" template:
Red/Version 1: Gold, Ruby, Diamond, Black, X, Sun, Sword
Blue/Version 2: Silver, Sapphire, Pearl, White, Y, Moon, Shield
But there are exceptions which are worth a quick look at:
ORAS-Palkia/Dialga: The first Legendary Hunt, I guess it shouldn't be too surprising there would be an exception as they were figuring things out. So, why Palkia in Omega Ruby and Dialga in Alpha Sapphire? I'm wondering if they were maybe more trying to match Legendary by not Version 1 & 2 but by colors? Omega Ruby's Legendaries were "lighter/warmer" colors: orange, red, pink, & white; Alpha Sapphire's were "darker/cooler" colors: blues & black. when you lined them up they all nicely went together.
Mysterial Teams: Now the interesting thing is that the Pokemon all do match-up with their Version number and whichever Gen II remake is linked, but it's the actual Gen IV version which is switched. I can only guess that they wanted to throw the opposite version Gen IV Pokemon at the player as they would likely be using at least the native caught Legendary. As for why they didn't do this for the Gen II remakes, remember that though we associated the Tower Duos with a specific version you can still catch both of them in the game, they didn't start doing version exclusive Legendaries until Gen III. And, if you're wondering, Platinum just uses the Diamond/SoulSilver team (my guess is that they only programmed the Diamond & Pearl teams and, to make Platinum and HGSS compatible, when linked to Battle Revolution Platinum & SS is programmed to have an id of a Diamond game and HG as a Pearl game).