My kids are shrimps and definitely recoil averse. To get them going I used trail boss in a couple youth model .243 that would put a 58 GR VMax to about the same POI at 100 yards as an 85 TSX. Trailboss and a light bullet makes for almost no recoil and they can plink at rocks, milk jugs, etc for a long time without getting sick of it or flinchy.
When it is time to hunt I switch to the 85 TSX. Has worked well for me.
When they are big enough to go to the elk woods I switch them to a Ruger Frontier 7mm-08. The heavy barrel on the Frontier helps tame recoil/muzzle jump and all have made the transition smoothly.