can a minor be charge if he is out past curfew but is with people that are 18 or older but are not his guardians?

Yes, a minor can be charged if he or she is out past curfew. In your situation since the adult is not a guardian, then this may be found to be an incorrigible act. 

Generally, you can be out past curfew only if you:

• are with your parent or guardian.
• have prior permission from your parent or guardian, in a motor vehicle traveling to another state.
• have prior permission from your parent or guardian, and are in an employment activity or going to or returning from an employment activity by the most direct route without any detour or stop.
• are involved in an emergency.
• have prior permission from your parent or guardian, and engaged in reasonable, legitimate, and specific business and/or activity.

BUT, every city has its own laws regarding curfew. You can look under the Curfew topic of the SpeakUp! section to see if your city's curfew is listed.