Charles requires you to proxy your device's networking through your computer, which is annoying to set up, and doubly-so if you need to sniff https. PonyDebugger looks great because it doesn't interfere with the normal networking behavior.
Except requiring you to compile it into your app. Presumably you're not including it in every build configuration, but that means you can't run it against just any build.
I think it only does outgoing requests, but rvictl can also be handy for inspecting iOS network traffic. With a single command on your Mac, it directs device traffic through a network interface on the Mac. Wireshark works great on it.