Colress makes only a small appearance in the original version of the Sun & Moon arc, but that was published before the volume release (the true/complete version of the manga), finished the Black 2 & White 2 arc.
The volume release is currently in the climax of Omega Ruby & Alpha Sapphire. With the volume ending of B2W2 revealing that the Colress who goes to Alola is actually Blake in disguise, we can probably expect the volume version of SM to expand upon that.
Alola is currently the only main region without a native Pokédex holder, as Sun is from Kanto and Moon is from Sinnoh.
We still don't know why Blake had the DNA splicer (the thing that fuses and separates Kyurem with Reshiram or Zekrom) as an infant in a crime scene.
That could be tied into the Aether Foundation plot, or even Necrozma's fusion with Solgaleo or Lunala.
by pokumbre