Are there any ATC-related items that pilots must be certified on? In other words, I understand that pilots have to successfully handle certain scenarios in the sim, like engine failures, instrument approaches, and so on, in order to retain their credentials for flying. But are there any such requirements for ATC interaction? Do pilots have to prove that they can follow instructions or provide information to ATC in some particular way? My impression is that no such requirements exist, but perhaps they do (?).
Personally, I should think that you'd want to periodically verify that pilots can follow ATC instructions. This would especially be true for pilots who don't have English as their native language, if they fly internationally (although all international pilots should be tested equally, even if English is their first language). That would be a safety issue and thus worth testing, perhaps formally. I've read that the ICAO is working on stricter standards for this but I don't know the details.
Of course, a full-motion sim is perhaps a bit over the top for mere ATC practice, but it's a realistic environment in which you could put pressure and distractions on pilots to make sure that they can still communicate in emergencies (it's extremely difficult to speak a foreign language when one is distracted by other mental tasks).