3) upper body bites

For the puppy the majority of the work is biting the legs, but I like to mix in a few armpit bites with a removable puppy sleeve periodically.  I do this with something completely blocking like a tarp or towel set up across a jump or something.  The puppy is on leash teased for the leg bite but then when you step laterally behind the tarp or towel you attract the dog up and target it for a proper armpit bite.  The dog learns really fast to redirect to the open target instead of being fixated on where the leg went.  Balance these into sessions periodically doing more as the pup is older so they can transfer their target on a dime and as they are coming fast downfield.  This technique seems to be more and more popular as the accessories used in mondioring get more and more dense in what the dog would have to plow through to find a leg.  Leg fixation at that point will lose many points for "slow to bite".