Hey! So right now, I can only answer the part for setting a new Terrain Field. For the part "I want it to be set for next battle also", right now it's not easily feasible, unless you had some things to the Battle Info. In any case, your code lacks some things:
- First, you don't need the rewrite ElectricSurge's code in your custom code, only do that if you have to modify something.
- Second, you have defined the Ability RadiationSurge, but you don't seem to have created the proper Effect. Check this file to see how it's done : scripts\01600 Alpha 25 Battle Engine\04000 Effects\01200 Field Terrain Effects\00100 Electric.rb
This link should help you too : https://gitlab.com/pokemonsdk/pokemonsdk/-/blob/development/%23%20PSDK%20.25%20BE.md#how-to-register-a-field-terrain-effect