Per son need to have great experience may be 20 or 20 + year's experience would be good
Person need to be 60 % on architect and 40 % on developement side
Architectural design experience
Experience with CMDB & Asset Management
Experience with Integrations and Service Portal Development
Knowledge of ServiceNow best practices and common anti-patterns
Mentorship experience
Consulting Domain Required
All 3 are necessery Certifications: CIS – Discovery & Mapping, CIS - ITAM & CTA certifications ( a person with maximum Certification including these 3 too )