>>46744012This is actually a clever nod to the fact that antlion larvae are stronger than their adult counterparts.
The larvae are the ones who build traps and spit bits of sand to catch bugs, and when they go through metamorphosis and change into their adult form, they're really weak and basically just exist to have sex and die. They can't even eat and are extremely fragile and terrible at flying.
And fun fact: antlion pits are easy to escape from for flying insects, but one of the few flying insects that can't escape is the adult antlion because it's such a weak flier.
TL;DR: Flygon is competitively unviable because it's literally built for sex.