Nintendo owns part of Niantic
Pokemon Company also owns part of Niantic I believe, and Nintendo has a 33% direct share of Pok Co. Gamefreak (?) I think it is also has a stake of Pokemon Company and Nintendo AGAIN has a significant stake in that company as well
basically long story short is that Nintendo has a very large stake in the Pokemon Co and most likely also has a large stake in Niantic at this point due to that.
Bear in mind the success of Pokemon GO is arguably mainly due to the fact that it is the first real game to come to mobile that bears the Pokemon brand NOT so much due to the software from Niantic. Its fairly basic at hte moment, and to be far Ingress was not really a big hit.
People just like Pikachu and Charmander and co. its that simple.
It is a big hit for Nintendo.
its a big weird how Nintendo owns significant portions of all of these random smaller companies but when you add up how everything is cut up Nintendo is most likely the majority share owner of them all. Pokemon Co and Gamefreak without a doubt and then Nintendo has some sort of decent stake in Niantic itself
Courtesy of Aquamarine, Nintendo doesn't own anything of Gamefreak, they are wholly independent, but Nintendo does own 35% of Creatures Inc., the third holder of The Pokemon Company shares. This gives Nintendo a total ownership of 43% of The Pokemon Company.
Meanwhile, Nintendo directly owns an estimated 4.44% of Niantic themselves, while The Pokemon Company owns another 4.44%. Since Nintendo owns a big part of TPC, they indirectly own a total of 6.4% of Niantic.