SPOILER WARNING: The following article contains major spoilers for Batman #42 by Tom King and Mikel Janin, on sale now.
In Batman #42, Catwoman shows off some serious moves by taking out three different Flashes in a matter of seconds. It's an incredible feat to defeat the Flash, but to beat three of them seemed a little over the top to some fans. People want to know how exactly Selina Kyle was supposed to defeat three superheroes who can travel at the speed of light. Tom King isn't telling, though he did assure his fans it makes perfect sense if you follow the clues.
Kind does offer the hint that the answer is already explained in the book, so this isn't a matter of Catwoman simply being overpowered for plot purposes, and when you pay attention, it's actually fairly obvious. In "Everyone Loves Ivy," Poison Ivy has taken control of the entire world, aside from Batman and Catwoman. The two set out to defeat Earth's new overlord, so Ivy dispatches the entire Justice League to stop them.
King and artist Mikel Janin show that Ivy has complete control over the heroes, to the degree that she can even speak and listen through them as her conduits out in the world. When Batman and Catwoman are out and about, she uses a mind-controlled Superman to follow them around town. Instead of fighting, Ivy simply uses Clark as a listening device to keep tabs on her enemies.
When Batman is ready to enact his place, he knows exactly how he can defeat Superman at this point. He pulls Catwoman close and whispers into her ear. At this moment, we see that Superman is focusing his superhearing on what Bruce is saying. Batman then turns the tables with a simple whistle, which proves to be devastating to Clark -- but why?
As Batman explains it, "Clark knows when to listen and when not to listen." As in, he has a better control over his power than Ivy does. He would have been able to avoid listening in on Batman's whistle had he not been under the control of someone who doesn't fully understand his powers.
It's a small moment in the grand scheme of things, considering it doesn't keep the Man of Steel down for long. However, it's an important event that sets up Catwoman's confrontation against the Flashes on the next page. Bruce and Selina know Barry, Wally and (other) Wally are coming, but they also know the Flashes aren't coming with their A-game.
All three speedsters come hurdling toward Selina, and while a fully functional Flash would almost definitely be able to avoid her attacks, Ivy doesn't know how to. It should be noted that Catwoman doesn't so much attack them as she reacts to where they are going to be. She defeats Barry with a clothesline, and the other two basically run into her foot. Catwoman uses their momentum against them in impressive fashion, but for a gifted fighter like her, it's not an impossible feat.
If we can use a baseball analogy for a moment, it might be easier to understand. It's nice to have a 95 mph fastball, but if it's coming in right down the middle of the strike zone, and the batter anticipates it coming, it's pretty easy for even a semi-talented player to make contact. The Flashes might normally be able to throw in a curveball or slider, something to fool the batter (Catwoman), but Ivy can't do that. If she can't control Superman's hearing, she's not going to be able to maneuver all three Flashes at the speed of light.
So while King refused to explain how this all worked out on Twitter, he gave us the answers in the book itself. That's the more important part, because it's plainly laid out how Catwoman was able to do what she did. Ivy may dominate the world right now, but Batman and Catwoman are still in complete control.