What are ideas for types that kind of make sense but GF would never implement because it's too specific and/or not wanted

>Fungus type

for anyone that has taken a couple biology classes, it may seem silly to put fungi pokemon like foongus or shiinotic under grass type. Fungi have nothing to do with plants, their cells are more similar to cells of animals than to cells of plants. For the sake of a children's game though it may confuse them why mushroom creature isn't a grass type.

Would also like to see rare mons based on odd chemicals like ammonia or sulfur-based compounds. Sounds stupid but you have animal pokemon who otherwise have nothing to do with water other than being given its elemental properties (panpour being an example, as oppose to something like magikarp which is simply a creature who lives in water). Some poison types would be a lot more interesting if their toxic properties were centered more on something like nitrogen dioxide instead of "muh toxic purple goop".