Pachy' don't deal large amounts of damage but their attacks will deal torpor. When fighting in the wild don't engage packs large then 3 if you only have basic weapons because they will knock you out quickly then have their way with you.
Tamed my pachy on craggs island, called it slappy. They are quite slow but the charge adds some speed in short bursts, I charge until out of stam and them set him to follow while he gets stam back and charge again, knocked out a couple of dodos while charging.
My tips are to use a bola if you have one to keep it in one place then knock out using stones on at tanqs. If you don't have a bola try finding one in an open area and pelt it with stones. To avoid its attacks run around in circles and reverse your movement when it is catching up or when it charges just walk out of its way and you can pelt it with stones while it charges as it is rather slow.
A easy way to tame a high level is to build a 1×1 stone structure with 3 windows and a door. They can go through door ways if no door is in place but can't fit if a door Is placed even while open. The 2 ways to get it in the trap is either with an argentavis or lure it in while your inventory is empty except for a door, once it is in place the door then wait for death and respawn at a nearby bed or sleeping bag. You will have to either use said argentavis to pick it out or remove the door and whistle it out once it is tamed.