>>42943617I can explain this. It's just a matter of priority.
First of all there was no chance Flygon was ever gonna be Flying. It's just not. They have no problem dropping Flying Typing the very moment they want two other Types instead. There's a million Pokémon who should be part Flying, but aren't because Flying is barely even a Type so much as a battle condition, and they never prioritize it.
So why were Ground and Dragon picked over Bug? Well, Ground is very important because of what Flygon was meant to be. From the beginning Pokémon has decided that all things sand and desert related (except Sandstorm for some fucking reason,) are always Ground Type. The desert in Hoenn was kind of a big thing back then.
https://www.youtube.com/watch?v=85t-XbzRzTAFlygon was designed from the ground up (haha) to embody the desert. Flygon needed some way to be immune to Sandstorm's damage, or else it wouldn't make any sense. (Looking at you Maractus.) They could have made it Flying or Bug and given it Sand Veil, but they just decided Ground was more thematic for it. And this way it has access to STAB Earthquake.
ALSO, remember what the beginning of this line is. Trapinch's main thing is that it digs sloped, conical traps and burrows in the sand. So really it has a lot to do with the ground, and that Type was at the forefront of their mind when they designed it. That was the cornerstone of this Pokémon line, that they are desert-dwellers.
Why Dragon and not Bug? When Flygon is CLEARLY based heavily on ant lions??? Well, because Flygon's not actually an insect.
Look at Flygon. It's BASED on ant lions, but it isn't actually one. It's just inspired by them. Vibrava 100% looks like an insect, I'll give you that. But Trapinch doesn't in the slightest, and Flygon is only evocative of one. It has eyes that EVOKE compound eyes, but aren't really. Wings that SEEM like dragonfly/ant lion wings, but aren't. Horn/hair that only appear from a distance to be antenna. It's a dragon.
