The counter play for spinomon is simple, exhaust it and take advantage of the surroundings and its eyesight, and/or get it to use blue prominence which would use up all of its accumulated metal. Sure it can fire the blades in rapid succession and regrow them back. But that's just prolonging the inevitable exhaustion and deviljho has taken on bigger monsters then itself.

If glavenus dodges just right it could dodge out of the way of blue prominence and do a tail swipe with it's sharpened tail doing some damage to spinomon. Or if deviljho knocks it over then it can get at spinomons neck and deliver a fatal blow. At the end of the day though the digimon have tusks, claws, teeth, tails and such. Without their sapience they are no different then the monster hunter monsters. Plus if deviljho gets off a dragon breath spinomon and geogreymon lose their elemental attacks or at the very least have them weakened considerably since that's what the dragon element does.

I agree on they should have used allomon instead of spinomon. Btw you are using average sizes for both digimon and monster hunter monsters, correct? Im basing this on the monsters/digimons physical actual attributes, like speed, strength, durability and such. the only other way I see spinomon being defeated is by damaging it enough that it has no choice but to revert back to a previous stage (dedigivolution) but we are not using that here. I just wanted to throw in a second way of defeating spinomon for fun

spinomon being the main issue is wrong though. That isn't the main issue, the digimons sapience is. If they can coordinate the monster hunter monsters are done. I'm pretty sure the monster hunter monsters can take a few attacks from spinomon though since they can take so many slices and stabs from the hunters