Monotype Pokemon now get double stab bonus
I was trying to think about how to make single type Pokemon stronger given that almost all the best typings both offensively and defensively are dual type and it feels like a lot of monotype Pokemon have an inherent disadvantage. Dual type Pokemon benefit from two types of stab and can tera into a third entirely different type or further buff one of their stab types. Whilst there are some dual types which combo two bad types and are therefore arguably weaker than their individual typings usually these two types combined are still slightly better than the individual mono types (something like frosmoth isn't awful even though it's bug/ice)
The idea would be to make a monotype Pokemon deal 2.25x on stab moves i.e. 1.5x1.5 (open to reducing this to something like 1.75 or 2x bonus but it seems less intuitive logically). I think this works better than for example amplifying the typing chart and treating a Pokemon as fire/fire for example and being 4x weak to water.
I think it would be op in some contexts especially like pixelate hyper voice Sylveon in doubles or eruption typhlosion but I do also think it makes some Pokemon that were pretty out of meta more useful and gives monotype Pokemon more of a distinct identity as being particularly representative of their type.