Answer to both Questions are in this quote here:
In Pokémon Rumble, Shiny Pokémon may rarely appear. They will always tip over when defeated. The chances of their appearance are unconfirmed, although they appear to occur more often than in the main series. Shiny Pokémon are always given a special trait, a blue name in menus, and a star below their picture on the Collection screen. Some Shiny Pokémon can be obtained by the use of passwords.
The link is here.
Hope this helps.