With Wormhole Potion, you can teleport to any member of your team in multiplayer. Keep in mind, though, that this is a potion, which means you'll use up one every time you teleport. However, you can stock up plenty of it in advance by making them at a Placed Bottle or Alchemy Table by using these resources: Blinkroot Bottled Water Specular Fish

Teleporters can transport players, NPCs, and enemies instantaneously. The Teleporter used to be purchased from the Steampunker, but as of version 1.4.4 you can purchase it from the Mechanic for 2 gold and 50 silver coins. The Mechanic is found after killing Skeletron, and you can find her in the Cavern layer or below in the Dungeon.