What are the Battle Items even supposed to be?

[Adelon]

Despite the fantastical-sounding English names, it seems that potions and elixirs are literally just ordinary medicine. Bulbapedia suggests that revives are based on Konpeito candy. And lemonade is actually supposed to be some sort of milk soda?

But I can't find anything about the inspiration for the X Items. Their Dream World artwork makes them look like pills but the Chinese (Cantonese) name for X Speed refers to it as a tool rather than anything like medicine, and the Wonder Launcher seems to suggest the same. too.

 

[Okido]

I was always under the assumption they were pills. The TCG art for X Attack and X Defense pretty much seems to depict them that way too:

Spoiler

(Upon closer inspection, it looks like whatever's inside an X Attack also closely resembles konpeito.)

Maybe they're vitamin supplements of some kind, perhaps related to the EV-boosting vitamin drinks?

 

[Palamon]

Maybe they're supplements/temporary steroids of some sort? Since they wear off when you switch the Pokemon out.