[Script] (Help) Static Pokemon appearing and disappearing

[Isuckatthisgame]

As of now I have overworld static encounters (like legendaries and stuff) working just fine but I have no idea how to make them appear only after you beat the champion or some other trainer (Example: Zapdos showing up at the powerplant in hgss after you beat blue).

Less important but I also don't know how to make the event reappear after after disappearing so it currently just vanishes permanently when fainted.

Edit: I somehow forgot to mention that im romhacking emerald...

 

[Pyxal]

As of now I have overworld static encounters (like legendaries and stuff) working just fine but I have no idea how to make them appear only after you beat the champion or some other trainer (Example: Zapdos showing up at the powerplant in hgss after you beat blue).

Less important but I also don't know how to make the event reappear after after disappearing so it currently just vanishes permanently when fainted.

Edit: I somehow forgot to mention that im romhacking emerald...

Just take any flag from the champion script, slap that baby as a checkflag in a Level Script in the Map where the legendary PKMN is, and done. :]