I’ve always thought their reasoning for Dark and Ghost was something along those lines, yeah. I didn’t originally tie Bug in with that, but it becomes pretty clear when you look at the ability ‘Rattled.’ As for the meaning of all those types… well, there are only a few that I associate with more abstract ideas like that (definitions for Fire, Water, Grass and so forth are really quite straightforward). I sort of think that, if more types were defined in that kind of way, there’d be a lot more freedom in designing new Pokémon, because you can tie a Pokémon’s element to its personality rather than its specific powers. Still, here are a few:
Fighting – ‘honour’ is part of it, but I don’t think it covers all Fighting-types; I think that Fighting Pokémon are the ones who are most like humans in their attitude to combat. They’re the most likely to fight for a cause, the most likely to consider fighting a skill worthy of exaltation, and the most likely to spend a lot of time training. Some, like Poliwrath, are more about athletics than combat, but they still have a more human than animal view.
Ghost – I think that a lot of Ghost Pokémon aren’t actually ghosts per se. Some clearly are, but I believe most of them simply have the name because they have powers related to death, the dead, and fear of death.
Dark – Dark is tricky, because there is something of an instinct that it should represent actual physical darkness, and Umbreon (one of the only five Dark Pokémon who existed in Gold and Silver) is very strongly associated with the moon and the night, the way Espeon is connected with the day. These characteristics aren’t actually shared by most Dark-types, though. The Japanese name literally translates to “evil type” and that’s the unifying theme of it: Dark Pokémon have abilities related to treachery, malice, fear, and brutality. This is not to say that they are universally evil – but they are pragmatic, and likely to use methods we might associate with evil.
Dragon – Back in Gold and Silver, one of Clair’s gym trainers described Dragon-types as “Pokémon that are overflowing with life energy” (or words to that effect) and that’s the definition I’ve used since then. Dragon-types aren’t necessarily connected with any one cultural stereotype of what constitutes a ‘dragon’ (just look at Altaria, Kingdra, Vibrava, and Shelgon). They are what they are because they have a special connection to some sort of ‘life force’ (which, I will remind you, is a very real thing in the Pokémon universe), and this is the source of their spectacular powers, incredible vitality and long lives.
Does all that sound reasonable? I’m sorry I don’t quite have what you asked for, but for most types it really is a lot simpler than this! There are definitely ways you could shift some other types in that direction, though – associating each Psychic Pokémon with an aspect of the human mind, for instance, or broadening the associations for Fire (which, at present, normally has only connotations of speed and destruction) to include warmth, nurturing, creativity, and passion.
Pokémaniacal 