Pantheon has a wind up with his W and isn't exactly going to be in the backline trying to help peel for his carries. It would be a large waste of his potential as an initiator and one of the best backline destroyers. Cho isn't necessarily a popular pick though... He has a 7.7% in Gold and above, 6.9% overall pick rate. He's in the top 46 most picked champs, but... that's 45 other champs more popularly picked.
Lissandra is a popular pick, also a popular ban due to her high amount of CC and she is a direct counter to Katarina as well as any Assassin really since she removes their ability to Assassinate with slows, a stun, and a root. Her entire kit is pretty scary for assassins, so she's a logical counter, just like she's a logical counter to Zed, LeBlanc, and really anyone who throws out a combo to burst one person down. Due to her kit being very anti-assassin as a whole, you could use that logic to say no assassin would ever need a nerf because Lissandra exists.
Other picks that can counter Kat are Ahri, also a popular pick, but if she charms, she's no longer a threat to Kat. Fiddle, but he dives into your team so you can dive their backline in the mean time. Alistar, but he's not only uncommon, but he's on very large cool downs, having about 10 seconds. Lulu is a good choice, as she is against all Assassins. Soraka if she's not the main target to begin with and instagibbing due to innate squishiness. Kassadin if he's ever picked anymore, having a lower pick rate than Zac.
I mean, there's lots of insta-CC's, but most are on very large cool downs and there's very few that are actually a direct counter to a Katarina and most of them are who gets to face her in lane, which is the problem right there. If that person is taken out of the fight early or has to use their CC early or not on Kat, then they've now failed their job in countering Katarina.
There's very little counter play to Katarina. When a champion is labeled as 'Beat them in lane and GG' or 'You need instant, hard CC' and is balanced around ONLY that, that's not balancing. If your mid has to pick before Kat and doesn't choose Lissandra, Cho, Ahri, or LB, they're in for one hell of a laning phase because Kat can escape from nearly any gank if she just uses the laning phase to farm much like a Jax and Irelia would. Bad early games are hardly an excuse for giving some one a nasty late game. We've seen that problem with Ryze who got gutted to the core while trying to fix itemization with his kit. We saw this with Veigar who had to have his reliability nerfed, which went overboard. We saw this with so many champions.