Fucking what?
You seriously think High Jump Kick's 130 BP is the only way Pheromosa is strong enough to work in OU?
Where the hell does the Flygon comparison even come from here? I'll humor the comparison to show you not only why it doesn't work, but to put Pheromosa in perspective.
1. Pheromosa has a Base 151 Speed. That outruns a number of SCARF mons in OU, not to mention Mega Alakazam and Aerodactyl, mons whose explicit purpose is going fast. Flygon is Base 100, which is a crowded Speed Tier at best and an insufficient one at worst.
2. Base 137 Mixed offenses is still pretty fucking high on a mon without losing the item slot. Flygon in your comparison is Base 100/80, which is not enough to run a mixed coverage move, or even mixed at all, especially without an offensive boosting item.
3. Bug's not a great offensive typing, but consider also that the Bug STAB of choice is U-Turn, which only has to work to serve its purpose of momentum grabbing, and hits hard besides in a similar manner to Genesect. Flygon needs Dragon Dance to function offensively, so U-Turn's never gonna be anything but a pivot move for defensive sets, and it never presents any pressure on its own.
4. Beast Boost. Pheromosa's most effective general role is that of a Cleaner, meaning Beast Boost only makes it harder to impede the longer you take to properly predict and counterplay against it. If the Scarf set gets an offense boost, nothing's beating it without Priority. Life Orb with a Speed Boost is running circles around everything and only going to get stronger. Not even Flygon, there are very few Pokemon with that kind of Snowball effect, and not many of them pile it on so easily (only one I can think off hand is offensive Magearna).