Does Aristophanes mock his characters?
This is a great question and the answer is very clear. Aristophanes mocked his characters greatly. In fact, the mocking of characters was essential to Greek comedy. In almost every work Aristophanes mocked his characters. Let me give you a few examples.
In the Clouds, Aristophanes mocks Socrates. He says that Socrates is just a sophist that confuses people. He is able to make weak arguments strong and strong arguments weak. It is all about rhetoric, the very opposite of what Socrates was trying to achieve!
In the Knights, he mocks the great statesman, Cleon. In fact, a sausage seller vies with Cleon for supreme power. Cleon is reduced to a bumbling fool and his lineage is questioned as well as his abilities.
In the Lysistrata, the mockery is broader. He mocks all the Greek soliders from Athens and Sparta for not being able to put an end to the Peloponnesian war. The women create a sex strike, until the men could make peace.
Finally, Aristophanes even at times can poke fun of the gods. For exmample, in the Frogs, Dionysus deplores the condition of tragedies and so he goes to Hades to bring back Euripides. However, his slave Xanthias comes off far smarter, braver and rational than the foolish god, Dionysus.
As you can see, no one, is spared, the gods included.