Skeetendo

I'm trying to work out how to make it so that a Pokémon in the middle of using Fly can be hit by Gust, Thunder, Whirlwind, et al. and a Pokémon in the middle of using Dig can be hit by Earthquake, Fissure, et al., and suffers double the damage from Gust if Flying and Earthquake if Digging. I'm pretty sure it's in the engine's battle core, but I can't quite put my finger on what lines of code to add and where to add it.

On a related note, I know what I need to write to make Stomp always hit a Minimized Pokémon as Swift et al. will always hit any Pokémon, I just don't know where to write it, let alone how to make it so damage from Stomp is doubled.