>>20850182If you stop changing you have your true bro. Also, having a favorite from the gen you started playing should sharpen your bond with that Pokémon, like Ash and Pikachu for example.
I played Pokémon Red, got a Nidoran early (back than I didn't know anything about it and had a hard time playing the game since English is not my main language, at age 7), so I trained it, it evolved, I used Trash and Earthquake to beat everything, it was the first Pokémon I got to level 100, it was the holo card I pulled from a card pack. I started doubting whether Nidoking truly was my ultimate bro in gen 5, since after all, new Pokémon were released. I played a nuzlocke at the time, got a Nidorino/Nidoking early. At gym 1 it was the only Pokémon that survived, at gym 2 it was the only Pokémon that survived with exactly 1 HP. After that I got a good team and blazed through the nuzlocke with Nidoking leading the team. Any doubt I had was gone. It is as if it was fate.
Our bond is unbreakable. I don't care if the next gen introduces the best possible Pokémon for me imaginable. It won't change my favorite. I stick to my buddy no matter what.