The way the multiplayer plugin works is explained through 4 tutorials that can be found in the manual article.
You could have a single sprite object, but displaying a different animation (if the controls are pretty much the same), and using "Send message" action in order to let the host know what animation/object type is to be assigned to what peer (using the PeerID expression in order to identify the peer).
This likely will mean keeping some array from your host's side, in order to know what PeerID is associated with what animation
The same think applies if you want to spawn/associate a specific object type instead of instances (the tutorials display how to use instances but the logic is the same for you if you want to rely on different object types).