Just to double check, once you get the Burned Tower upgrade, you
are able to get both Retro Lugia and Retro Ho-Oh eggs? Or is there
a second upgrade I'm missing?
(Just me sobbing in my 9 Lugia and 0 Ho-Oh eggs...)
From the wiki “If you were lucky enough to win an upgrade during
the Johto Apricorn Battle, you are also able to find Retro Eggs
that might hatch into Retro Lugia or Retro Ho-Oh.” I guess you’re
just really unlucky :P