Hi Ines,
I think the short answer to your question is, "yes, you can have anyone be your co-host"; however, it would be to your benefit to hire someone with experience in hosting or co-hosting short term rentals. It's not absolutely necessary for them to have experience with the Airbnb platform, but it would be great if they did (especially, if you don't know the platform yourself). A co-host can be local to your property or can be remote (in a different city and/or state). It comes down to your preference and if you feel comfortable with the person and their experience.
I have been a host for a year on a property I own in the same state in live in (California), but it's 5 hours away from my primary home and I have been able to successfully run my business.
If you're interested in chatting about how I can help you, let me know.