Greg is meant to be a wall you run into again and again in The Sims 4, especially if you are working through the Lone Wolf aspiration. He hits hard, shrugs off most fights, and usually walks away as if nothing happened.
Beating him is less about luck and more about showing up prepared.
Get Fit
Start by making sure your werewolf is strong enough. Fitness matters a lot here. Aim for level nine or ten, so your Sim can last longer in a fight.
On top of that, unlock the Alpha Wolf ability. That perk directly improves how your werewolf performs in brawls, and it makes a noticeable difference against Greg.
You really want to reach the Apex rank before challenging him seriously.
Your Sim can’t just jump straight into fighting Greg. They first need to show they’re tough enough by beating a few other werewolves. Doing this also helps boost their morale and fitness before taking on the big challenge.
Get the Right Temperament and Mood
Temperament also plays a role. If your werewolf has the Big Bad Wolf temperament, your odds improve. It gives you a more aggressive edge, which helps when you are up against someone as strong as Greg.
Right before the fight, eating a Luna Fish can give you a small boost as well.
Mood matters more than people expect. Go into the fight with all needs taken care of and try to get your Sim feeling Energized. That mood helps with stamina, and stamina is everything in these brutal fights.
You can get Energized in a few simple ways. A protein plate works well. Coffee helps too. A brisk shower can do the trick if you are in a hurry. Any one of those is enough, so pick what your Sim likes best.
Be Persistent
Even with all of that, do not expect to win on the first try. Greg is designed to beat you down repeatedly. Each loss still helps you build skills and push closer to a win.
Keep training, keep coming back, and keep challenging him. Eventually, all that prep pays off, and you will finally see Greg go down.
And if you ever get tired of fighting him, there is always the softer route. You can choose to befriend him instead. Greg is rough around the edges, but he does not have to stay your enemy forever.
Happy Simming!