For those who obtaind the lab key in wrong order causing to get stuck at Lysandre Labs B3F
i figured it out!!
I used someones save file that hasn't obtain keys and
compared the save file before after they obtained
Basically you need to modify ur save file with pkhex to:
After openig ur save file go to SAV > items > key icon
1. Remove key items (Lab Key Card A, B, C, Elevator key) - set to value '0' and uncheck anything related
go to Event Flags tab
2. uncheck 1 value under 'Event' tab - DD09A5AF5869E155
3. uncheck 4 values under 'Field Items' tab
FF919BF7529EB09C - Lab Key Card A
FF919DF7529EB402 - Lab Key Card B
FF919AF7529EAEE9 - Lab Key Card C
FF919EF7529EB5B5 - Elevator Key
then save and obtain in order! you should be good to go!!