Guardianship Accountability Act of 2018 This bill provides resources to support individuals who are at least 18 years old and who are placed under guardianships because they are unable to make safe and sound decisions. Specifically, the bill requires the Elder Justice Coordinating Council to establish a National Online Resource Center on Guardianship. In addition, the bill expands a demonstration grant program for elder abuse prevention to include grants for collecting information about guardianships, training court visitors, and sharing guardian background checks.