The Nintendo Switch Console is expected to enjoy optimal charging over USB Type-C using its own Nintendo Switch AC Adapter that comes with the Switch. The Nintendo Switch AC Adapter uses USB Power Delivery over USB Type-C to provide 7.5 watts (5 volts @ 1.5 amps) and 39 watts (15 volts @ 2.6 amps) of charging to the Switch Console.
When directly plugged into the Nintendo Switch Console, the Nintendo Switch AC Adapter starts communicating over USB Power Delivery with the Switch at 7% full battery by declaring its source capabilities of 7.5 watts (5 volts @ 1.5 amps) and 39 watts (15 volts @ 2.6 amps).
The Nintendo Switch Console requests an initial 7.5 watts (15 volts @ 0.5 amps) charging power and is accepted by the charger.
The Nintendo Switch Console is then seen to request the highest PDO of 39 watts (15 volts @ 2.6 amps) from the charger which it also complies.
While being charged from 7% battery, the Switch Console starts off drawing around 15 watts (15 volts @ 1 amps) from its own charger during the first 10 seconds without any active gameplay (the Console is just left alone being charged without the Joy-Con Controllers being attached).
Not surprisingly, this power is much lower when compared to using the Switch Dock in another review which consumed more power from the AC Adapter to support the Dock's HDMI and USB ports being used while simultaneously running active gameplay.