I think the Blossom should have an ability that makes it immune to poison types. I also think other grass/poison types should have this type of divergent evolution

Because I think of it as being purified of it’s poison. I hate that it goes from being a poison type to being weak to poison types. I think a later Gen should give it some sort of major buff.

As for the second point, i think it would be fun for Pokemon like Weepinbell, Amoongus or even Ivysaur to have these types of what i call “purified” evolutions. They can be their own little new group without really changing up the whole game that much.