She was a beast, but nobody was as strong as Kasparov when he was in his prime. While Polgar could be considered an elite and a legendary player compared to other women, she's elite only for her era. Kasparov was elite among the elites. There are only a handful of players throughout history who were comparable. People like Carlsen, Botvinnik, Fischer, Morphy, etc... Even among these players, Kasparov's strength in his prime probably titled toward the higher end of the spectrum. When you talk about prodigious strength, he makes prodigies seem weak by comparison.
Fischer was, and a few more. Karpov, Capablanca, maybe Schlechter and Tarrasch etc. Not Morphy, Carlsen or Botvinnick, who were very strong but still second tier.
She was a top ten player in her prime, beat him at least once that I can remember.
Never in classical, once in rapid i think.
Unlike him, she wasn't allowed to undo moves.