PSVR is an add on to the PlayStation and cannot be used with out one. The PSVR is the headset only and those controllers were previously purchased separate. The PlayStation camera is also required to work with the PSVR headset, but some bundles include the whole thing (headset, camera, controllers and possibly even earbuds). Some bundles included one or two games as well. Users with a PlayStation account have access to various free PSVR games as well. SO if they have a PSVR, they have a PlayStation.
What type of controller is required depends on the game, but a baseball game for example, likely would use that controller, called "Move" controllers. Many work with a standard controller as well, but some will require Move controllers specifically.
I am not aware of any good baseball games for it though.