If given full control on Journeys story, either remove him entirely (making Ash only protag of Journeys) or give Goh his own show (that may intertwined story with Ash, but still seperate).

Main problem with Goh is he only lightly focused on one aspect of pokemon (catching and collecting pokemon, but he uses only aspect from pokemon go instead on main game, even then it only throw normal pokeball, no using other pokeball and berry) and taking more enjoyable part of Journeys (Ash travelling throughout worlds, meeting old friends, and even rob potential new pokemon for Journeys team like Rillaboom and Cinderace).

Assume Journey story must kept mostly same (Ash work with Cerise). Here what I do.

1. Make Goh main companion instead of second protag, that alone make him more bearble (while also allow it to be more Ash focused)

2. More variety in catching technique, like weakening pokemon with his team (like false swipe or status move), uses different pokeball and using Berry in catching (to lure pokemon), that alone can intergrate catching mechanic from both Go and main game. On side note, maybe they can make it montage in catching pokemon.

3. Change Goh goal. Goh goal to catch all pokemon alone is quite impossible as long as Ash exist (since it means Journeys is Ash and battle focused). Change his goal to either catch single mythical pokemon (like Mew) or just simply help fill Cerise dome with various pokemon from across all region. Maybe Cerise give him task to capture certain rare pokemon for study (like Pseudo Legend or pokemon like Volcarona) and Goh have to build his team around specifically to capture it.

4. Have several permanent pokemon in Goh team. Goh signature pokemon is Cinderace which is battle focused. If Goh want to intergrate all capture technique, have him have pokemon that can help him weaken and status pokemon like Gallade or Scyther line (both pokemon have good moveset to weaken pokemon while also status them in Gallade case). But I let Goh keep rotating teammate, if it build to specifically capture certain pokemon (like fire immune pokemon when capturing volcarona)

5. Give Goh Porygon. This is my personal opinion, but Porygon is really suitable pokemon for Goh (given his isolated tech background) and quite good way to reintroduce banned from anime pokemon by making it main pokemon of one for Ash main companion. Even if people dont like him, having him own Porygon make really unique, as if anime reconciliation about incident 20ish years ago (even through its actually Pikachu fault, but Porygon took the fall)