The fastest solution would be to use a Thunderbolt 3 to Thunderbolt 2 adapter connected to a Thunderbolt cable. The Thunderbolt 3 end will connect to your new MacBook Pro and the Thunderbolt cable will connect to your old one. This isn't a cheap solution, however. But it is by far the fastest.
This is the only real option you have for a cabled transfer*.
Other options are Wi-Fi (but very slow) or to transfer your stuff to a USB hard drive and copy it to your new one using a USB-C to USB adapter.
*You could use a mish-mash of adapters involving ethernet but this would be slower and more expensive than the Thunderbolt solution.