Why do people always say it's basically just Hoenn again? It's literally as different from Hoenn as you can get while still being a Japan based region. Do people just say this because it kept a lot of the elements introduced in Hoenn, like berries, contests, double battles, etc? Because it brought back a lot of gen 2 features as well, but no one ever calls Sinnoh a Johto rip-off. If anything I feel like Sinnoh was supposed to combine elements from all 3 of the prior regions;
>150 mons in the dex and the most common mons are all from Kanto.
>Day/Night cycle, cross-gen evos, and mythological focus like Johto.
>Overall similar "structure" to Hoenn, while carrying over features staple features like berries and contests.
There's also a lot of minor call backs like Professor Rowen returning from Kanto, the secret potion being what you use to heal the psyduck, and so on. It's what makes Sinnoh feel like the "ultimate" pokemon region.