Bowser does know what a cat is, and after squinting to see the sketch in the dark, he recognizes the creature in the drawing as one. He nods as the professor explains, still looking at the drawing.

"And there are Pokémon powerful enough to do something like this? How powerful are normal Pokémon, then? How powerful are the Pokémon Blue or Lance has?" If he was going to battle Blue at some point, as he and Blue had agreed, Bowser should find out just what he's up against, assuming Samuel has that information. And with how much stronger Lance's Dragonite had seemed than Blue's Eevee, it made Bowser wonder how strong these creatures were.