The phrase "rotational basis" means that something is done in a cycle or rotation, where one person or thing takes turns or alternates with others. Full definition
So rotational basis I use to make this cake in different flavors. (uryummyrecipes.com)
US personnel will come on temporary and rotational basis in relation to activities that will be held in AFP facilities. (ghanapoliticsonline.com)
The only difference between the Animal Farm and Organized Real Estate is that with Organized Real Estate the horses come and go on a regular rotational basis, but their overall numbers remain high enough to keep the money ball rolling and thus keep the pigs (the overseeing ruling class by fiat) happily rolling in manure... I mean, money. (remonline.com)