Zestful allows you to designate team administrators that can give rewards or manage the team members (or any combination of these 3 tasks) of any team that you create.
See how to create a team in Zestful here.
Create a Team Admin
Once a team is created, head to the Teams tab and click View on the team in question.
Click on the Team Admins tab to create or manage team administrators
From here, you are able to
Add new team admins
Delete existing team admins
allow/disallow admins to give rewards to the team
allow/disallow admins to manage team members