Before i get to tank Cynthia's Garchomp Outrage, Lucario's Bullet Punch, Roserade's Petal Dance, and her Milotic's Hydropump. I will say this. Even though Cynthia would pretty much curbstomp in this poll, I'll do my best to still show some love for Lance.
I remember Lance being so cool when he actually came by and fought alongside the player in both gen 2 and gen 4. Lance as mentioned previously did something productive against the bad guys. He even had his Dragonite use Hyper Beam on a rocket grunt because that's how pissed Lance was during the whole situation. He was willing to go that far, and i love it when they do that.
Of course, Cynthia pretty much wins as an in-game "boss" for her respective game because she pretty much got the proper treatment from gamefreak to have a lineup that wasn't only good on paper, she is the only in-game trainer in any game in the core series to have an entire lineup with Perfect IV pokemon, something that a true Pokemon League champion would actually have to establish being the game's core "final boss" before the credits roll. Of course, most casual players who dont' give shits about IVs or EVs or any "complicated pokemon data related matters" wouldn't know but they would just wonder how come their team of at least lvl 50 to 60+ pokemon got their chests kicked by Cynthia's team.
As far as the in-game teams go, Gen 4 was a missed opportunity for Lance to have an initial lineup that would actually be good. The whole 3 Underleveled Dragonites gig was pretty much getting old, and i guess gamefreak thought that players in HGSS would already go to the Pokemon League with their party on the early to late 40s with 50 being their highest levele'd member, and along with lance, I still question why HGSS was still that underleveled like how the majority of Gen 2 was. It would take going through more of the game to actually see a lineup for Lance that was actually good or at least way better looking on paper than 3 Dragonites and 3 not-Dragons but still cool and fit the whole "Dragon and Flying" theme well. Also, why didn't Lance get the perfect IV pokemon that his contemporary counterpart did. It still bugs me up to this day. If Gamefreak deliberately gave Cynthia a lineup of perfect IV monsters, why didn't Lance get his?