Ampharos comes from Ampere, a electric measurement unit, and Pharos, a lighthouse that was one of the seven ancient wonders of the world. Nothing to do with dragons.
This doesn't negate the Japanese name, which is obviously the original, but let's not go looking for etymology when it isn't there.
So they have actually prioritized the light house part when they do the translation, was guessing that they will do a direct translation instead.
From bulbapedia:
A lot of weird ability/move distributions makes sense when you use their japanese names (for example pretty much everything with wings getting Heat Wave, which is "Hot Wind" in japanese, or butterflies and moths getting Quiver Dance which is "Butterfly Dance"). Still doesn't help explain why manaphy gets Tail Glow ("Firefly Light") though.
Concerning Manaphy, if you have actually watched the movie, you will know that the two spheres at the end of the two antennae of Manaphy literally "glows". You will also know that Manaphy lives in the deep sea which is a dark environment. And despite making not any sense at all from an evolutionary aspect, Manaphy relies on its eyes to sense the world and light up the sea with the light from the its sphere.
As said above, the deep sea is a very dark environment, but the light coming out from the two spheres is very bright and can be seen from a far, which actually resembles how the fireflies seem in the night. In fact, firefly is exactly named after "weak light" in japanese, but I guess GF decides to respect bugs here instead of some fire or electric stuffs. Anyway, as a side note, "tail glow" is exclusive to fireflies, not everything with their tail glowing.
Just to mention another one here, "draco meteor" has nothing to do with dragons in japanese either, it is just that the first part of the pronunciation of "meteor fall" happens to resemble the pronunciation of "dragon".
Anyway, with regenerator, I expect to see it in two scenario.
One is the semi-stall teams, likely built with specially defensive and spreading paralyses to cripple special sweepers, it only really fears ice type btw, and dragon type provides some very usable special resistances. Earth weakness is unfriendly but you often see that on the physical side and has little to do with you.
Another one is on pivot teams which has three or four voltturners (the one I am currently toying with), with that level of bulk it can easily switch in after the voltturn chain is broken(a misprediction, or after scoring a kill, etc.), and restart the snowball of momentum with a slow switch. It is also good in the sense that it can provide cleric support, something that is very difficult to be thrown into a voltturn emphasizing team, though it is not necessarily used all that often, and would have been better if it can use draco meteor instead. Or perhaps wish, which is even better.