Let's talk about Fallers.

Based on in-game text, Fallers are characters from the Gen 3-5 universe (the "previous universe") that were thrust into the Gen 6-Gen 7 universe (the "Megaverse"), likely by the same power that caused the UBs to be forced into the world from Ultra Space. At least two Fallers have been placed in significant positions in the International Police.

Anabel is most definitely a Faller, and now a high-ranking member of Interpol.
Looker is almost definitely a Faller, because the way he washed up on the Battle Resort with no memory matches the description provided of Fallers. He was also already in Interpol in Gen 4 and 5, and likewise claimed to be in Interpol in XY.
Grimsley probably isn't a Faller.
Colress COULD be a Faller, but there isn't much evidence to suggest it.
All the other characters are almost certainly straight from the Megaverse versions of their regions (Red, Blue, Wally, Cynthia).

It's very likely that future games will expand upon this concept.
Could there be other Fallers?
How exactly were they forced from their original universe?
Does this have anything to do with the technology used to create the Link Cable in ORAS?
Will we see Fallers from the Gen 1 and Gen 2 universe?
WILL IT ALL COME TOGETHER?