My 16yr old boy is like that. He’s hard to wake, struggles to get organised and is super slow in the morning. I shake him awake 75 minutes before we have to go, so he has plenty of time.

Set their alarm an extra half hour earlier to give them extra time to get up.

My husband would sometimes bang 2 saucepans together. Or sing until they get up.

Earlier bed time? My bedtime was always 9pm in high school, so I’d be awake easily by 6:30am to get ready for school. It worked for me!
Get an alarm and set it to beep every 5 minutes, and if that still doesn’t work a good knock on the door until he responds?
Threaten with the cold water trick if that doesn’t work

Regular bedtime routine and also a set routine during the morning.

Multiple alarm clocks that go off at 10 minute intervals.

Turn the light on and open the curtains to wake him up,good luck!

I would also suggest an earlier bed time. If this still does not help after a period I would have him visit the doctor as he may well have a sleep disorder.

Be consistent with the time he goes to bed. My daughter is 15 and she’s in bed every night maximum at 9. The alarm is at 6 am. She’s fine with it, even if she’d prefer to sleep a little longer. Who wouldn’t??