When a Riolu hatches from an egg how do you make it to be shiny form?

You can't make a Riolu hatch as a shiny form. Whether a Pokémon hatches shiny or not is determined when the egg is obtained.

Here's how shiny Pokémon work:

* Random Chance: The odds of hatching a shiny Pokémon are extremely low, typically around 1 in 4096.

* Shiny Charm: Having a Shiny Charm (obtained after completing the Pokédex) boosts the odds slightly to 1 in 1365.33.

* Masuda Method: This breeding method, involving Pokémon from different regions, increases the shiny odds to 1 in 683. This is a popular method for trying to get shiny Pokémon.

You cannot influence the shiny chance once the egg is obtained.

There's a common misconception that hatching eggs at certain times or performing specific actions can influence shininess. This isn't true. The shiny status of an egg is determined the moment it's received.