I've been trying out pyramid head and think I'll probably main him. I thought I'd compile some tips and advice here, while also giving everyone an opportunity to discuss in the comments. Also, this is my first discussion board so please be nice lol.

Pyramid Head is super heavy. He's not a zoner, but he isn't all about being in your face either. His ideal range is when he can hit you and you can't hit him, so try to play keep out whenever you can. Your range is your best tool and you don't have a fast "get off of me" tool, so stay in that ideal range where your opponent is in danger and you aren't. Note that your opponent will be forced to be much more cautious if you are in torment range, since you have armor on your attacks.

Down tilt into up tilt is a pretty reliable combo that can set up a juggle. Pyramid Head is a lot scarier in the air than you'd think, but his aerials are slow. Focus on prediction and covering large areas. Up air can juggle but has a small hitbox so you need precision. Forward air and neutral air function pretty similarly to eachother: They can kill and they cover a large area, but have long windup. Use fair for more kill power and nair for more coverage. Also, use aerial side B! It's fast, has good range, and can make for an easy kill confirm if your opponent is tormented. (Tormented side B > fair near edge)

Pyramid Head is powerful in the air but he's still slow. Approaching with short hops isn't great in my experience, and you're better off using your F tilt to play keep out, D tilt to start combos, and F strong for hard reads. You can also approach with side B, but this can be easily interrupted unless your opponent is tormented.

Neutral B is a good way to apply torment, but back air seems to be the best way. For the spear moves (dstrong, bair, utilt) you have to hit the sweet spot. With utilt and dstrong it's very hard to since the spear is angled and you're grounded, but with bair the spacing is a lot easier. Just try to hit with only the tip of it. Bair should be a big part of your neutral, as it lets you get torment and play keep out. Also, jump and then use neutral B to change where it lands, since you can't angle it.

Press the advantage. Pyramid Head is great at landing multiple hits in a row because he covers so much ground. When your opponent is offstage you can absolutely bully them by using nair, fair and neutral B to stop their approaches and force them to try recovering again. Remember to stay in your ideal range as well as using side B on tormented opponents to get kills.

If you have any more tips or want to correct something I said, please speak up in the comments.