I don't even have a pretend answer, at least not for teams. They do not exist simultaneously and do not receive starters from the same batch that the PC does. Even then, that would only be the starters. Not to mention that there is already a starter triad within the games that has nothing to do with the other PC. (yes, I totally make this same argument for gen 5) Then again, the ones that people pretend to exist don't really have a lot of credence either. The female protag of FR/LG does not exist within the same timespace. There is actually no one that takes the third starter in the second gen, and the opposite gender protag doesn't take it in HG/SS either. They have a Marill instead. There is also no third party in the third gen for any incarnation of it. Wally also gets his own starter that is not of the three. Gen 4 is the first place it really exists. You and the opposite gender protag exist within the same timespace and share the starter triad with your rival. I don't know BW2 that well, but I don't believe there is a third party between yourself and the rival that gains a starter. In the 6th gen, you all literally gain your starters at the same time as your opposite gender rival and Shauna.
Only two instances where this relationship actually exists in the games and everyone insists they must all have it.
