>>50478854I'll give you an actually optimized answer.
No matter what, you're gonna need to transfer Pokemon from Gen 1 in order to get the elemental stones, so you need one of those.
The Pokemon not available in Crystal are
>Vulpix and Ninetales>Mankey and Primeape>Mareep, Flaffy and Ampharos>Girafarig>Remoraid and OctilleryVulpix and Mankey are the only ones that are not available in both versions of Gold and Silver, Mankey is Gold exclusive and Vulpix is Silver exclusive, while the others are available in both.
Since you're gonna need to play both a Gen 1 game and a base Gen 2 game the best way to go about this is to choose the Gen 1 game where the opposing exclusive Pokemon is available.
So, optimally, you'd go with
>Pokemon Red for Mankey, the Kanto starters, the elemental stone evolutions and the legendaries.>Pokemon Silver for Vulpix and the non-Crystal Gen 2 mons>Crystal to complete the rest of the dex 
