Dratini, Dragonair and Dragonite obviously follow the "Dragon" part, but what's interesting is the second part. "Tini" is a messup of "Tiny", in reference to Dratinis size; "Air" is thought to refer to the fact that the tiny wings on Dragonair's head can actually be used for flight, as seen in the anime; I don't know about "Dragonite", but I think it's just to make it sound impressive, and I could swear it was a reference to something mythical if I could just remember what. Originally, I believe, these three were the only dragon-types in the game, which is why Lance's original team consisted of two Dragonairs, a Dragonite, and a Charizard, a Gyarados and and Aerodactyl, the latter three being dragon
like Pokemon who have also turned up in his subsequent teams. It's probably because of their strength, rarity and heavy references to mythical creatures that they are demi-legendaries, and ridiculously hard to train and defeat. This is also probably why one of their two weaknesses is themselves, the other being ice. (You asked for info, you got it
)
Magnetmite, Magneton and Magnezone obviously derive their names from Magnet, but the "mite" in Magnemite refers to it being small, while "ton" in Magneton refers to it being large. The "zone" in Magnezone is likely just intended to sound weird and sci-fi, as it is in the image of a UFO. The former two were originally pure electric types, but helpfully became dual steel (and thus weak to fire) around the time that they commonly gained the "levitate" ability, making them immune to ground-type moves.
I did see the Magnet Rise attack (VERY helpful btw)
I favour fire types ♥