Why Does Sans Remembers Resets?
The Resets He Mentioned Were Caused by Him Being Discovered by and Defeated by Sans. Sans Is Aware Something Keeps Reseting the Timeline But, Unlike Flowey...
The resets he mentioned were caused by him being discovered by and defeated by Sans. Sans is aware something keeps reseting the timeline but, unlike Flowey, cannot Save and does not keep memories of other timelines. He doesn't know of Flowey's identity (or perhaps even his existence) in any timeline in-game.
Does Sans know about the resets?
Sans gets a little memory from non-true resets, but literally every other major character does. The only difference is Sans is AWARE ABOUT EXISTENCE OF RESETS and of course he'll give those pieces of memory more importance. But that still doesn't mean he remembers literally everything.
Is Papyrus aware of the resets?
Sans and Papyrus seem to be aware of resets. Fandom. Sans and Papyrus seem to be aware of resets.