Imagine if Uncle Owen escaped the Imperial cookout that lay in store for him and his wife and instead toured the galaxy in a blue milk induced rage, taking part in bare knuckle brawls all across the empire. If I had to choose a person from each movie that I reckon he could give a serious ass whooping to, my choices would be thus:
No contest. Tarkins biting wit and hatchet features would have little baring on the moisture farmers sun baked knuckles.
"I told you to forget it."
Sure, he can manage an entire city/mining colony with his mind, but can he dodge a sand encrusted haymaker?
"There'll be hell to pay."
I don't think Ackbar can make much of a fist, sure he could probably give you hard slap, which would no doubt be akin to getting slapped across the face with a dead mackerel, but I don't think it would be enough to put down our Owen. He'd knock Ackbar into orbit around Endor.
"I'll make it up to him next year."