JaKSLaP To emulate these games you have to use the LibRetro’s MAME 0.228 core or the GroovyMAME 0.232 standalone emulator in your Batocera .32 ×64 version. However, I’m not sure for Killer Instinct and latest Tekken games are properly running.
.dat files contains an XML tree describing each emulated games and their required roms. There is a lot of information like the checksum. This value is usefull to check your roms are all right and ready to play with your MAME emulator. To check your roms are clean, you will need to use a tool like ClrMamePro.
So to play your MAME roms with the LibRetro’s MAME 0.228, you’ll need a valid MAME 0.228 romset. The .dat file let you check all your roms are compliant with the 0.228 requirement. Like the same, with the GroovyMAME 0.232 emulator you need a valid 0.232 romset.
Each month MAME provide a new release. Current version is 0.237. Each new version can emulate more games and fix some issue. Then you need to update your MAME roms to be compliant with each new release.
You can find additional information here : https://wiki.batocera.org/arcade