i would say lets start off with us all getting called to a special plase bye a mystical voice in our head that only we, the choosen ones, can hear. evrybody says how they got there because some need to maybe travel a bit further than others and then the god pokemon just tells us something and after that we like start a journy. if we have enough maybe we can split up in diffrent groups so that the gods are like having a competition because they want to get the praise from the god we rescue and maybe some want to travel in small groups.
btw for the pokemon that send us i would say like smaller legendarys like suicune entai raiku or the birdys. And i would say that the evil god has someone like that too. maybe hes working together with like keldeo virizion terrakion and cobalium or the birdys or just in general smaller legendarys. maybe even heatran because hes just fat and ugly .-.

if you want i can try to write a thingy how we start of.