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Pic related was a lot better than "Goodbye Pikachu" because, as a story, it stemmed from Goh's inability to connect with and understand Raboot. All Goh wanted out of Scorbunny/Raboot was to be a best friend and show affection. He didn't respect his Pokemon's desire to be independent and achieve new things, he thought that simply 'accepting' Scorbunny was enough. Scorbunny had to learn Ember independently, with no help from Goh.
When Goh felt rejected by Raboot, he was told it was simply a 'rebellious phase', but I think Goh had to earn Raboot's respect and trust back. When Goh supported Raboot's dance battling and actively participated in trying to help, Raboot got what it initially wanted as a Scorbunny. Even further, Goh demonstrates growth in deciding to separate from Raboot-- Because he WAS deeply wrong in how he was going about raising it, wanting an adoring companion over a partner he works hard to support. This decision was imperfect, mind you, as he didn't ask Raboot what it wanted, but it was interesting and showcased a growing empathy in Goh.
Meanwhile "Goodbye Pikachu" was completely isolated fake drama. A bunch of Pikachus appear. Ash sees Pikachu having fun with them. Ash suddenly decides Pikachu is better off with other Pikachu and runs off crying. Then Pikachu comes back. This is not set-up by other episodes nor does it mean anything to Ash's character.
