Gengar should have had dazzling gleam
Niantic have said "Fighting-type opponents won't stand a chance against a Gengar with telekinetic power!" Even though Gengars current moves will do more damage against fighting types than Psychic will! Needless to say, Niantic have laid a total egg here.
The simple solution would have been to give it dazzling gleam. Dazzling gleam is a much better move than psychic without getting close to matching shadow balls neutral DPS. But at least it would edge shadow ball out vs fighting types. Dazzling gleam is also more likely to be weather boosted. It also makes Gengar a possible option against Dragons.
Dazzling gleam would have been a much better and more interesting choice that is by no means a strict upgrade on shadow ball. Psychic offers Gengar absolutely nothing, Dazzling Gleam would.
Answers
While you are right that Dazzling gleam would be a better choice, it's pretty obvious that Niantic doesn't want to give Gengar a situationally better move. They just want to give Gengar another exclusive move. There's no way they didn't know Psychic is strictly worse than Shadow ball, it was obviously intended
Only collecting value, probably the point is getting trainers to raid and get a shiny. I think the exclusive move is just something extra they just threw in the mix
Perhaps they thought "hey, Gengar is already a very powerful Pokemon, it already has an amazing legacy move and doesn't even need RC, let's not give it any other powerful move".
Besides, if they really want to release the CP rebalance we saw, Gengar will greatly benefit. I just think they don't want to give him any more power for balance purposes
They need to realize that these 3 actions in a row had put themselves into thin ice and it just makes them and us look like fools to begin with:
* Community day exclusive move "Redemption" (And mass server errors)
* Gen 4 pokemon getting the worst possible moves
* Legendaries and fan favorites being nothing other than a waste of storage space.
gen4 pokemon didn't get the worst possible moves, just legendaries and sub-par atm. Yet, I agree they will probably milk it legendaries and fan favorites through exclusive moves during community days and raid days.
You can still enjoy current legendaries they are not at their full potential but definitely serviceable or keep candies for eventual exclusive release
