Shining Jirachi Lucario GX interaction

[Mitrox]

Hi! I want to know the following order interaction between this cards.

Shining Jirachi-Psychic type - Stellar Reign 10 - If your opponent's Active Pokémon is an evolved Pokémon, devolve it by putting all of the Evolution cards on it into your opponent's hand.

Lucario-GX 210 HP Weak to Psychic / Riolu 60 or 70 HP, depending on the version.

Shining Jirachi attacks to Lucario-GX with Stellar Reign plus a Choice Band. The damage is 40X2=80, and then devolving the Lucario, knocking the Riolu. The question is, the order resolution is always like this, or can it occur a situation of the effect coming first and then, doing only 20 damage to the Riolu?

Thanks!

 

[PokePop]

Unless the attack text specifically says to do an effect first, "before doing damage", damage is always done first, and then other effects.