Skeetendo

i have to some  some questions
1=how do the trriger work(i mean if i made a custom trigger how can i make that only a certain person move?is there any relation between them?)(through pksv)
2=what are flags(is the flag mean you need a certain item to proceed or anything else?)
3=trainer scripting(through poksv)
4=pokemon event(pksv) like a pokemon sat before the enterance
of north star in dark energy
please help me coz i having problems with this
few more= how to make an event to give pokegear by another person instead of mom or pokedex by other in place of oak.