Every character gets gestalt but one class MUST be Summoner(Normal Summoner not Unchained) their Eidolon also gains what ever their secondary class is. However the only divine classes allowed are Cleric, Inquisitors and Paladin/Anti Paladin(so no Druids, Hunters, Rangers, Oracles, etc.) and if you pick an arcane caster you can not use conjuration nor evocation spells, if you wish to do damage with spell like effects you will need to play the Kineticist.
No characters should be recreations of those in the show/manga as those should be npcs in the world. Recommendations for character are Divination Wizard for Mr. Joestar, Unchained monk for Jotaro, Fire Kineticist for Avdol, Swashbuckler for Polnareff and Water/Earth Kineticist for Kakyoin.
The Eidolons will act as the summoners Stand and thus should receive DR infinite/Eidolon and have energy resistance to fire,cold,electricity,acid,positive and negative energy of infinite vs anything that is not another Eidolon.
Stats should be a 30 point buy however every character automatically get an 18 strength and charisma pre racials. Every one should also have two favored class bonuses one being Summoner and the other being whatever other class they pick.
The world setting should take place in about late 1990's early 2000's and every boss should also have gestalt with Summoner being one of the classes.