If you take battery cables off does the system have to be reset before it'll pass smog?

there is no reset. anytime you disconnect the battery,the computer resets to factory settings and when the battery is re-connected all readiness monitors are set to NOT READY and will NOT pass emissions testing until a drive cycle is performed and all readiness monitors set to READY. normally 50-150 miles of stop and go driving,around town,interstate driving,heat on/heat off,A/C on/A/C off,1/4-3/4 tank of fuel. we don't have smog testing on 1995 and older here in NC,only safety inspection,although on 1996-2000 we can have two monitors not ready and still pass.CA use to have the same,but was changed around 05-06 to only one not ready and you would still pass,if I remember correctly? https://repairpal.com/how-to-perform-a-basic-drive-cycle

Recommend purchasing a battery tender so the battery doesn't have to be disconnected for extended durations of vehicle being parked..