All out habitats/biomes

So, we`ve been seeing a lot of "problems" regarding Pokémon habitats with the Kanto birds these days; many reports of entire towns where nothing spawns, no Articuno sightings yet (at least as far as I´m aware), and so on and so forth.

I´m wondering if this is going to be the same with all the other legendaries during the weekend, because it would be a shame having the chance to find your favourite/the best legendaries in the wild just for most people finding absolutely nothing (I know they are legendaries and meant to be rare and all but still).

All the info we have is "You may encounter almost all Pokémon in their natural habitat" and "Pokémon will appear in specific biomes based on their natural habitat and PokéDex entry".

Is there even any actual way to look for biomes/habitats? Or the only way to do this is the catch screen? Any way to check for biomes within your own town/region?

This is Rayquaza´s Pokedex entry for example "Rayquaza is said to have lived for hundreds of millions of years. Legends remain of how it put to rest the clash between Kyogre and Groudon." What information regarding its habitat is that supposed to give? How is the average player supposed to know?

I would love to know other people´s opinions on how this is gonna play out.