In the Gen 1 games and their remakes, Lorelei is a member of the Elite Four specializing in Ice type pokemon. Notably, she gets more development than the other members of the Elite Four, as in FR/LG we get to go to her home and meet some of her family. Yet in the Gen 2 games and their remakes, Lorelei is gone with no explanation, having been replaced by Will, a Psychic type specialist who has no backstory or origin whatsoever.
Lorelei and Will both use a Jinx and a Slowbro on their team.
Lorelei and Will both have a red and purple color scheme. Will's hips are broader than his shoulders. Their faces have a very similar shape, aside from what's hidden by Will's mask. Their haircuts are even similar.
In FireRed/LeafGreen, all of Lorelei's pokemon are female during your first match with her, but in rematches, all except her Jinx are male. Between Gold/Silver/Crystal and HeartGold/SoulSilver, all of Will's pokemon except his Jinx changed from male to female.
Pokemon Crystal has metadata that identifies trainers' gender, for the sake of dialogue sampling. Will is identified as feminine in this data.
Make of this what you will.
