Heck, the last time they made the transaction, there was this huge, amazing episode about it called "The Kids" where Gumball and Darwin struggle to fight off the idea that they're aging only to have their voices change over in the end as they realize they'll never grow up. ("Yay?") And thus, Logan Grove passed his part down to Jacob Hopkins, and Kwesi Bokyae passed his part to Terrell Ransom, Jr.
This swap, however, is quite jarring. There wasn't really a huge episode to explore the concept so much as Nicolas Cantu and Donielle T. Hansley Jr. just kind of stepped in, stole the part, and sent Jacob and Terrell to the curb. At the very least, an altered rerun of "The Kids" would've sufficed just to be timeless.
Still, it's kind of hard to be angry. The last cast was going through puberty pretty hard, and while they still were able to capture the childlike candor of the characters, there was a bit of a mental block that kind of got in the way of parts of it. (Knowing that the person who voices their baby sister, Anais, is a child actor that is a fair bit older than them kind of offsets the connection too.) Also, of all the final episodes, they had a lot of lukewarm, reheated ones. Here's hoping the production code is a bit shuffled, and perhaps a bit too optimistically, Jacob could return for The Copycats later on, because if he can't pull of a counterfeit Gumball, then I don't know who can.
So... the episode. It was good!
The basic premise is that Gumball is angry that his dad Richard mishandled his skateboard as he is, a skateboarder, much to the hilarity of the town because, y'know, he's clearly not. Darwin, regardless, believes him and asks to be taught to skateboard, to which Gumball obliges, seeking to teach Darwin every element of skateboarding aside from how to ollie, which we can surmise he's trying to hold off on as much as possible. In other words, it starts out with more of the same, but there's nothing wrong with that.