Active teenagers put their gear through it. Training most days, sport on weekends, long school days in between, and a washing machine that sees all of it multiple times a week. In my opinion, the best teenager underwear for active young blokes is the kind that handles that schedule without failing inside 3 months. It needs to breathe during physical activity, stay in place while moving, and survive the kind of rough washing that teenagers do.
A dad I know coaches junior footy and noticed that a few of the boys on his team were constantly fidgeting with their shorts mid-game. He mentioned it to a couple of parents and it turned out their teenager underwear was either too small or made from synthetic fabric that wasn't handling the summer heat. Simple fix, significant improvement. 1 of the boys went from constant distraction to playing a clean game the following week. Gear that works underneath makes everything on top work better.
For active teenagers specifically, teenager underwear needs to be cotton so it breathes properly during training. The leg cut needs to stay put during running and contact sport without riding up. And the waistband needs to hold position without rolling or digging in. Boxer briefs or trunks are the practical cut for most active young blokes. Loose boxers might feel comfortable but they don't handle athletic movement the way a structured cut does.
Barramundies makes teenager underwear in quality Australian cotton with the cuts that active young blokes actually need. It holds up long enough to cost less over a full year than cheap alternatives. If the young bloke in your life is active and constantly replacing gear, it's worth trying once. Good teenager underwear makes active days easier without requiring any thought at all.