Apple and Onion is the quintessential example of an average Cartoon Network show that I have not much things to say about it.
Let's clear the air first,
Sometimes it's really funny, sometimes it's really bland.
The characters sometimes are annoying but also not the worst I've seen.
The titular duo aren't bad all things considered.
Apple is a bland, dopey but not terrible protagonist. Onion isn't half bad either.
They are two serviceable protagonists that would be great as side characters in a completely different show.
The plots are nothing out of the ordinary and is very simplistic. The intro is fine, the music is mostly okay but can be cringe sometimes.
Some of the dialogues can be perfect as background noise.
And that's it really.
Overall, not a show that's bad but not a great one either.