You can't. If the Pokemon is loafing around(Slakoth and Slaking) then that just means it has the ability Truant. That's just how it works.
You can, however, pair it with a Pokemon that knows skill swap. Then, the slakoth or slaking would move every turn. Unfortunately, the other Pokemon wouldn't.
Chat with our AI personalities
There is a way to stop Pokemon from evolving. You let the Pokemon hold a certain stone.
There is no way to make it stop raining in Pokémon Ruby, Sapphire and Emerald. Eventually it will just stop by itself.
you have to catch or kill kyogre
If you accidentally pressed "B" while your Pokemon was evolving, all you have to do is level it up again.
You can't; its ability Truant causes it to stop attacking every other turn. However, if you are Double Battling then you can have a pokemon use skill swap on slakoth/slaking to switch its ability with the other pokemon.