According to Bulbapedia,
"Snom's voracious appetite in Pokémon Camp is likely a reference to Saturniidae biology, in which the caterpillars eat a large stockpile of food due to losing the ability to eat upon becoming moths."
I think that Snom could be:
Snow | frozen precipitation
Worm | soft bodied invertabrate
Nom | Slang for eating
I personally do not agree with Snom coming from "Moth", that's more it's evolution, Frosmoth for me.
I think it is probably Toxic, but Toxicity is another viable option I think.
"Toxicity: The quality or degree of being toxic". That's what I think.
I believe that it isn't Apple, but Apple + In. It's Sword Dex entry states
"It spends its entire life inside an apple". This means that it is a small Dragon of sorts living inside the apple. Just my opinion though, not sure if I am right :)
Just a small thing, "de" can mean of in some languages, so basically Togedemaru is Round of Thorns lol
Hope this is alright :D