Mineral Group
>A mineral is a solid inorganic substance of natural occurence.
Baltoy is modelled after ancient clay toys that are found at various archeological digs. Claydol is simply a larger one.
The Beldum line is obviously based on metal, particularaly steel, and magnetism.
Bronzor comes from the word bronze, a mineral, and mirror. Bronzong is modelled after a metal bell or gong.
Carbink is based off of diamonds, a type of mineral.
Cryogonal's a special snowflake. It looks like it should be in a Water egg group, being a frozen water droplet after all. However, it also resembles a type of crystal that I cannot remember the name of.
Honestly, this seems far fetched. Voltorb and Electrode do seem to be meant to resemble posessed Poké Balls, but that might be stretching the definition of "mineral".
These guys are based off of golems, huge clay desert monsters in Jewish culture. Correct me if I'm wrong.
The Klinklang line is a network of metal gears, much like clockwork. The steampunk Pokémon.
Lunatone is, quite literally, a moon rock.
The Magnemite line quite obviously originated from magnetism and magnetic metals, as well as electricity.
Porygon, Porygon2 and Porygon-Z are supposed to be man-made cyber-Pokémon. It doesn't fit with the definition, but, well, take it as you will.
I don't even know. It's a discarded bug shell that eats souls. We could go out on a limb and say that it could, eventually, become a fossilized bug shell that eats souls.
Not much speculation here — it literally has "rock" in its name.
Fairy Group
>A small imaginary being that posesses magical abilities.
It's a Fairy-type, mostly. Also, as I said before it was based off of diamonds, which are ofteen attributed with magic, etc.
Amorphous Group
>Without a clearly defined shape or form.
Nothing suits the definition of "without clearly defined form" than Rotom. The Poltergeist Pokémon will posess any piece of technology available.
Water 3 Group
>A transparent, odorless liquid.
They're starfish. That live in… wait for it… WATER!
List of genderless Pokémon.