STOP SAYING THINGS HAVE BEEN RETCONNED YOU MASSIVE BRAINLETS
Nothing has been retconned or ever will be retconned because multiple universes are now canon. Anything and everything can happen with the "AU lol" explanation.

Here's the current timeline for the MAIN universe:
FRLG = ORAS > HGSS = Pt > BW > BW2 = XY > USM

All the bosses come from timelines in which they were successful. Here's how those play out:
>Giovanni: RB or Y >= Nothing because Giovanni rules the world, or FRLG = RSE with Brendan/May winning but getting btfo by Giovanni
>Maxie/Archie: RB/Y/FRLG (Red beats Giovanni) = RSE >= Nothing because a massive portion of the world was flooded or dried up, seriously fucking with everything.
>Cyrus: RB/Y/FRLG = RSE/ORAS (both play out normally) > GS/C/HGSS = DP >= nothing because Cyrus made his perfect autistic universe
>Ghetsis: RB/Y/FRLG = RSE/ORAS > GS/C/HGSS = DP/Pt (all play out normally) > BW >= Nothing because Ghetsis rules the world as the only person with Pokemon
>Lysandre: RB/Y/FRLG = RSE/ORAS > GS/C/HGSS = DP/Pt > BW (all play out normally) > BW2 (ghetsis gets btfo) = XY >= Nothing because the world was nuked

Nothing has changed in the main timeline. So stop calling anything a retcon.