She just lost in a straight 1v1 tho
She lost to RL Laxus in a straight 1 vs 1, Laxus had to break out Red Lightning to win.
Thus Erza > Base Laxus (in a straight 1 vs 1, I maintain that base Laxus is actually the more deadly combatant to the average FT character).
What does Gildarts have suggesting he's > RL Laxus?
Laxus was looking to be his contemporary during Alvarez, and now he has a mode where he gets more powerful the more he gets hurt. Gildarts isn't beating that IMO, even if he can somehow crash all of Laxus' attacks (something I doubt given some of them are naturally combined with his physical ones) he has to actually put Laxus down. Outside of Erza, Laxus is one of the tankiest characters in the whole series.
If we're being fair to every character, Gildarts should be in the same situation as Jellal here. Does Gildarts have feats that top RL Laxus'? IMO, no. August was low-diffing him even with the amount of PIS he had in that fight and while being able to one-shot Hist Serena is a decent feat,
base Laxus has a superior one in one-shot killing Wahl. Add in Red Lightning where he just gets better the more he gets hurt and Laxus vs Gildarts would end in a similar way to RL Laxus vs Erza IMO (maybe easier on Laxus actually, since Gildarts hasn't shown himself to be the absolute tank that Erza is).
I'm no big Laxus fan (too macho for me + lightning is boring) but his recent feats put him ahead of anyone not called DF Natsu.