So I've decided to buckle on the concerns expressed regarding the cryostasis machine idea I had for Pokemon Purple, and make it a full-fledged time machine capable of going both forwards and backwards in time.

So here's how time's gonna work now:

There will be 250 years (3000 region states) for the player to explore. The reason given for the finite travel range is that the time machine can only travel throughout the time period that it exists in a functional state, meaning that the player can only use it to travel from the moment that the time machine became functional (after defeating the Elite Four) to the moment that it ceases operation (which conveniently happens to be in precisely 250 years).

The machine's travel through time both forward and backward can be controlled with month-level granularity, however there is an error margin of a few months. In addition, after use, the machine takes about a month to recharge.

Also, I'm toying the idea with giving the time machine a HIGHLY experimental option… the ability to actually reverse the flow of time itself. This results in Pokemon battles being completely flipped on their head… the start of the battle is the end, and Shinji 'undoes' the actions that led to that conclusion. Ex:

(Player walking around) -> (Random encounter: "Shinji defeated the wild pidgey!") -> (Attacks, items, pokemon are unused) -> ("A wild pidgey appeared!") -> Back to overworld.

If actions that the CPU undoes conflict with logic (ie Pidgey unused tackle and undoes a succesful hit but the player's Pokemon was at full health), a timeline deviation gauge fills up. Once the gauge fills completely, the battle ends and the player is randomly transported to one of several alternate timelines. After a month, the alternate timeline will collapse and Shinji will return to his "homeline". These alternate timelines can be home to extremely rare Pokemon and items, some of which may not even exist in Shinji's homeline.

The only tangible "benefits" of sucessfully undoing battles is that it can be used to de-level and de-volve Pokemon, as well as duplicate items (undoing the use of a Pokeball, for instance, means that you'll have one more Pokeball than when you "finished" the battle). Another benefit of reversing time, outside of battle, is unbuying items (better than selling, because you get a full refund).