Procedure to when an entity get spawned every entity in an x radius get teleported to it

• Under the 'on initial entity spawn' trigger, create a procedure.
• In said procedure, place an 'for each entity as entity iterator' block. This will allow the procedure to target all entities in a radius, instead of only the entity causing the trigger.
• Then, simply have a block that sets the location of the ENTITY ITERATOR to the TARGET ENTITY. The distinction between the two is important; the target entity is the one triggering the procedure; the entity iterator is each entity within the radius. 
• Keep in mind this will target literally everything, including items, projectiles, and the like; so you'll probably want to at least specify that this should only affect living entities and players, for example. 

You can actually do it much easier by just executing a command as the spawned entity. "/tp @e[distance=..5] @s"

You can change the "5" to the distance you need. If you don't want players to get teleported use the unless statement or add "type=" to the requirements.