Make it trivial to add Terrains to mapgroups and metatiles

[surskitty]

Description

It should be easy to specify what Terrain a battle will start with within a certain mapgroup, map, or metatile. For example, if I want all wild encounters in New Mauville to be Electric Terrain, it would be tremendously useful if that functionality was built in without having to fiddle with the var for Starting Status in map scripts.

Discord contact info

wildvenonat

[AlexOn1ine]

I wonder if we can as griffin for porymap support here

[surskitty]

I certainly would appreciate porymap support as well! But even if it isn't in porymap it's still useful if it's purely in code. In particular my vision includes adding a Grassy Terrain behavior to the very tall grass metatiles. I don't currently have any ideas that crave Psychic Terrain, Misty Terrain, Gravity, or Trick Room, but those would also be helpful to designate on map, mapgroup, and metatile levels.