sorry I can't remember what it is called
Nope, there are no legendaries in those balloons.
Please tell me if I'm wrong about the areas, I've never played Rumble World before, I just used Bulbapedia.
List of Pokémon in the Ember Mountains
List of Pokémon in the Dewdrop Bay
List of Pokémon in the Leafy Expanse
P.S. For the 3rd Balloon I assumed you meant the Leafy Balloon
The answer is NO. So I won't go on and on and on... It is kinda bad that you can't but I geuss you can't always get legendaries. Plus their are no Grass, Fire and Water legendaries that are related in a way.
I hope I helped