http://www.newsweek.com/monster-hunter-generations-ultimate-how-transfer-data-3ds-nintendo-switch-1091468

Monster Hunter Generations Ultimate is available now on Nintendo Switch, and players who owned the 3DS version can transfer their old save file to the hybrid console to continue their quest to become the strongest hunter.

The original 3DS version released back in July 2016, so there’s likely plenty of players out there with data from the original Monster Hunter Generations game. Capcom and Nintendo have made it relatively simple to transfer that data from to the Switch version.