Solrock normally learns Morning Sun. In PRO, it is not an option.

 

Pre-evo, Egg Move, Moveset... just somewhere please and thank you!

Solrock could only learn Morning Sun as a Dream World move in Generation 5. This means that a Solrock captured in Generation 6 or 7 has no means to learn Morning Sun. Furthermore, there are more pokemon that has a couple moves exclusive to Dream World, so if we give the move Morning Sun to Solrock, we'd also have to give every other pokemon their Dream World move.

 

If we are to allow pokemons Dream World moves, I see two ways to implement it:

 

1st. Dream World move tutor. Very simple to implement, but I feel like... it's too easy for the uniqueness of the Dream World moves?

 

2nd. In the same way as Hidden Abilities, each pokemons has a 5% chance to also have a Dream World move, assuming there's one they can learn. This chance would be increased to 25% with a Black Medallion. Of course, percentages don't have to be the same as Hidden Abilities.

 

The problem I personally see with that is that Gen 5, 6 and 7 pokemons were not given any Dream World move. So I have mixed feeling about having it introduced with half of the pokemons missing out on that feature.