We're not interested in tiny little changes here and there; doing that will make USUM glorified DLC. What we want is £40 worth of content that pays for itself. I'm not talking about five or six new Pokemon with a couple of new formes, I'm talking new music, new scenes never revealed, more island trials, the aforementioned return of Battle Frontier and none of the garbage Battle Maisons or Battle Trees, and the piece de resistance: adding 6v6 to all battle types in the Battle Spot; sick and tired of bringing a full team to only pick three and curse my luck when the opponent uses a Pokemon that isn't weak to any of my chosen Pokemon moves. Basically, I want this to be a new Alolan experience, putting the Ultra in Ultra Sun and Moon, and not just be Sun and Moon with just a fancy new title.

Crystal added the Suicune quest-line and introduced the Battle Tower into the series, but that was about it and overall it's basically the same game as the other two (it wasn't really until Gen 3 that the versions really started to have story differences).

Emerald added the Battle Frontier and made both Teams antagonists instead of one or the other and in terms of additions, outside of Black 2 and White 2 (which I don't count as they're technically sequels set in the same region), it added the most to the experience of any "3rd Version".

Yellow didn't change or add a ton aside from making it more like the anime which, while not necessarily a ton of new content, I think is more creative than what Crystal did.

Platinum didn't alter a ton about it's story but, like Emerald, it turned the Battle Tower into part of a Battle Frontier, so not super inspired but the BF is always interesting and the graphics/mechanics of the Distortion World were cool.

As mentioned before, I don't really consider Black 2 and White 2 a "3rd Version" game a sequel set in the same region, but if I were to consider it as such, I'd say it's the best one in terms of a unique and fun experience compared to the original versions because it has its own story and several significant changes and additions to the region's layout.