Will they mess with the typings?
I was just thinking - given we now have evidence that Niantic like to switch things up from time to time, first with the big CP formula changes in the Ditto patch and now with the big changes to moves across the board with the release of gen 2... could the next thing they mess with be the typings? I understand that the typings in PoGo did not strictly come from the original games? So Gengar could one day become pure Ghost type, for example? And maybe Gyarados could become part-dragon? Just some examples that could benefit those mons and would give them a buff without messing with moves or the CP formula. Possible? Or unlikely?
Answers
Ok understood, thanks. Total Pokémon noob here, still on the PoGo bandwagon, hence the probably-stupid question.
I think I got the impression they weren't from the original games just because I've heard and read a few complaints about Gengar being dual-poison typing and all the gen 1 rock types being dual-ground types and the effect that the typings have on their viability as defenders etc. I wouldn't have expected such comments given that the typings are completely set values. Maybe the complaints were also from people new to Pokémon :-)
Any complaints about something being double would probably be about double weaknesses. For example, dragon/flying being double weak to ice, or rock/ground being double weak to both grass and water.
Double weaknesses have always existed in every pokemon game and always affect the viability of a pokemon. In PoGo, having a double weakness to a common type is detrimental to a gym defender. This is why Rhydon (rock/ground) is not actually a very good defender despite its high CP. It has double weakneses to two comonly available types.
Regarding Gengar: In Pokemon Red/Blue, psychic was really overpowered. Ghost was supposed to be one of the answers for psychic pokemon, but the only ghost pokemon was ghost/poison and poison is weak to psychic... and there were no good ghost type damaging moves. Psychic being top dog with no viable answers in Red/Blue was why dark and steel types were added in Pokemon Gold/Silver.
I think the complaints aren't necessarily due to people being new to Pokemon with PoGo, but rather that they're complaining about general Gen1 imbalance that was later corrected.
e.g. complaining that the only ghost attackers are also Poison (so weak to Psychic) - new types and pokemon were added later that could beat Psychic.
e.g. complaining that the strong rock attackers (Rhydon/Golem) are also ground - better rock attackers without ground typing were later added.
Gen 1 was catastrophically imbalanced. It didn't really matter at the time though, because there wasn't technology for a huge PvP scene, Legendaries destroyed everything in game, good pokemon were generally rare (or at least hard to get) and once you got something it took a lot of work to max it out (even if you used a glitch for rare candies to get to level 100, your pokemon wouldn't have EVs gained from battling which equate to like half of their total stats).
They have never changed the CP formula, just the way the stats are calculated from the original games, which in turn change the CP of pokemon because CP is calculated from those stats. As for type, those too come from the original games, what's different in type advantage from the original games is the following:
Supereffective damage is supposed to be 2x normal damage
Not very effective damage is supposed to be 50% normal damage
Some types are invulnerable to certain types of attacks (Fairy to dragon, ground to electric, ghost to normal and figthing, etc) and some abilities grant inmunities to certain attacks (levitate to ground for example).
All of the moves pokemon in PoGo can learn, are only the ones they can learn in the main game series.
As for your Gyarados example, he becomes Dark type when he megaevolves so bite and crunch get stab when this happends, so that might happend some day, but mega evolutions were introduced in Gen VI, there's a long way to go before that.
As for changes the can make, they could change how supereffective damage works, to be at leas 50% more/less damage instead of just 25%. And inmunities could be better translated as 2x supereffective or something like that, the reason why inmunities are not in the game is because some pokemon are just ramdomly useless against other pokemon, but translating that to 2x supereffective is a good solution I think.