>>12641986>Azurill is completely changing typesWe don't know that yet. I'm assuming it'll be retconned to Normal/Fairy.
>Celebi changing from Psychic to Fairy.That's exactly what I'm talking about. You're going to have to pick one of its types to replace, and in effect, you're making a much larger change to a Pokemon's make-up then just slapping on another type.
And then you have the problem of what type to replace. Psychic? No, it has psychic powers and can travel through time. Grass? But it's the guardian of a forest and can restore plants and other Celebi's back to life.
This will have to happen for every dual-type Pokemon being retconned. Might be easier for Pokemon that are Normal/<another type> but then again GameFreak seems to be really emphasizing the importance of Normal with all these dual-type Normal Pokemon lately.