taking a neighbor who has a 20ga shotgun. We are going to hunt Florida hogs. Should he get a slug or 00 buckshot for shots of 40-50 yds?

Buckshot, not slugs

buckshot

Better count on the slugs. You can't get 00 in 20 guage I don't think. I would use the slugs anyway, if he has practiced enough and can hit a target consistently at that distance.

And in his excitement if he misses, or the hog is running around (like they usually do) ...

40 to 50 yards with #3 buck (the normal load for a 20 guage) I don't think is a suitable load for a 200 pound or so hog. You are just going to bugger him up most of the time.

slugs by far, looking at ballistics and thinking of the momentum capable of them!!!

Sluggers.

our hogs are typically 80-125 lbs, so not whoopers. I will buy both and be prepared. I am not sure he will have time to practice with the slugs so i am reluctant to use them

slugs all the way. remember hogs have a much tough skin then deer, and as we all know a much tougher animal, so go with the slugs.