We've associated nail trimming with positive rewards since our 5 month old puppy was around 8 weeks old, so he's pretty chill about it. He'll let you trim 3 feet without any issues. On the 4th foot he's pretty much done with our shit and starts pulling away, but he does let us do it. We just put him on a special table that is used for grooming him, and he sits there and lets us do his nails. He's also pretty ambivalent to shots, but again, we've always done everything we can to make these positive experiences for him, with lots of treats and praise. Brushing his teeth is equally as chill. It usually comes down to exposing the pupper to these things at a young age and making it an overall positive experience. He also went through a professional puppy socialization class for 6 weeks, to make sure he's cool with people and other dogs, since he's going to be a large and powerful dog when he's fully grown. He goes into advanced obedience training class in 2 weeks!