Pokémon Emerald Flying-only run
🍀 I must only use Flying-type Pokémon from the moment I catch the first one.
🍀 Other Pokémon can be caught, but only for HMs.
🍀 If a non-flying Pokémon acquires that type on a later evolution, I can catch it, but I will try to evolve it as soon as I can so it's legal.
As for why: Ice, Electric and Flying have always been my favourite types, but Ice and Electric are harder to come by early on.