It isn't a special case. Most the moves don't increase by huge amounts as you level them up. For example I'm in the process of lvling up mons on a mules. I just did a few Claw storms at various levels highers were 786 claw storm at level 30 (might actually be higher but kinda one shots anything in the peninsula) against an ep... 1207 at 60 then at 87 the best I could do was 1208 (1600 with MS)
Now that I've finished another project and am finally getting a mule back I might have time to throw into monstrosity to get some average mon move dmgs at 99 but for reference the highest I've gotten by far off of a normal xp mob not taking advantage of things like dmg type weaknesses or soul eater was with the spriggan at 90... was with mighty strikes but still 3114 aint too shabby when most moves wont even break into 2k and was on the same mob that as that MS claw storm and well you see how strong claw storm is at lower levels.
Regardless one thing to keep in mind before trying to transfer mon dmg over to potential jug dmg is you wont have things like instincts or job abilities or for some of them moves that enhance their attack. Not to mention even without that mons are just inherently much stronger all the way up you could just melee VTs to death fast enough to chain a jug would have trouble with EMs even if you kept throwing pet food at it.