That depends on whether you want to go realistic or stylized.
Tristan's hair is one of those YGO styles that could go either way, and you can either be brilliant or scary in both directions. His hair as drawn in the art is actually a highly stylized representation of a masculine buzz-cut. Because it's really difficult to find wigs that short in the first place, I can see where you would want to attempt to go full-on stylized with the sharp pointy thing. But you have to be really careful. Trying to do it that way will either be amazing or stupid. I've only ever seen one person pull it off successfully, but I think part of what worked for theirs was that they did their makeup and some points of tailoring their school jacket to also reflect the same sharp stylization, as if they were deliberately cosplaying a promo art picture version.
To get the pointy antenna...well, you still need a fairly short base wig. That part isn't going to be fun. The forward sweep is probably best done as loose hair or extra wefts sewn in and then sculpted with hair glue to go forward. Ani_Bee has a point, a triangular form underneath will help it not look dorky. Just be real careful with your proportions, don't make it too big and exaggerated.
Founder and Vice-President, Madison Area Costuming Society, a chapter of the International Costumer's Guild
Strange Land Costuming - www.strangelandcostumes.com
Director, SF&F Masquerade
- COSTUMECON34 - Madison, Wisconsin - May 6-9, 2016 - www.costumecon34.com