No, you would need 2/0 (2 ought) in copper.
In the US, 2/0 copper is allowed only in residential installations. Otherwise, 3/0 copper is required to a 200 amp service panel.
The electric utility can use whatever they wish. They have their own standards and the NEC does not apply to them.
The size of wire for service entrance conductors for a 400 amp 3 phase service could be 500 MCM copper. This is very large size wire and difficult to bend and shape, to connect to terminals in the main disconnect and distribution panel. This problem is solved by using parallel conductors or on higher ampacities triple conductors. Using parallel conductors the wire size would be three ought (3/0) copper.
A 200 amp service panel will require a # 4 bare copper ground wire.
Aluminium wire has produced problems due to unequal expansion/contraction at the brass or copper terminals and long-term surface oxidation. For that reason copper is recommended and there is usually no good reason not to use copper (of the correct gauge for the current).
I doubt if you can fit a 200 amp breaker into a 100 amp panel and it is illegal as the bus bars in a 100 amp panel are rated at 100 not 200 amps. The panel must be of the same capacity in amps as the main breaker that is installed in it. You can go smaller but not larger. The other problem is that a 200 amp service required three ought (000) wire. 000 copper wire with an insulation factor 90 degrees C is rated at 210 amps. Two ought (00) copper wire with an insulation factor of 60C is rated at 145 amps, 75C is rated at 175 amps and 90C is rated at 185 amps. Buy a complete house package that has the main breaker and all of the appliance breakers plus a few breakers for 15 amp circuits, all for one price that is cheaper that buying individual pieces.
This is a voltage drop question. A voltage value needs to be stated. Assuming that the 200 amp panel is a single phase 120/240 volt sub panel. A #1 copper conductor will limit the voltage drop to 3% or less when supplying 100 amps for 200 feet on a 240 volt system.
A 200 amp service panel with a 60 amp sub-panel.
Answer for USA, Canada and countries running a 60 Hertz supply service.CEC states that a #3 bare copper conductor is a common grounding conductor size for a 200 amp service panel and it is the minium size for service raceway and service equipment of 400 amps.
Typically copper conductors that provide a phase of electricity.
#6 bare copper wire.
AWG # 3/0 copper.
The size of wire for service entrance conductors for a 400 amp 3 phase service could be 500 MCM copper. This is very large size wire and difficult to bend and shape, to connect to terminals in the main disconnect and distribution panel. This problem is solved by using parallel conductors or on higher ampacities triple conductors. Using parallel conductors the wire size would be three ought (3/0) copper.
It is based on the amperage of the service panel in a single phase home panel useing copper wire use. 100 amp use AWG # 3 copper 200 amp use AWG # 3/0 copper
A 200 amp service panel will require a # 4 bare copper ground wire.
Aluminium wire has produced problems due to unequal expansion/contraction at the brass or copper terminals and long-term surface oxidation. For that reason copper is recommended and there is usually no good reason not to use copper (of the correct gauge for the current).
The short answer, if using copper, is 0 AWG, commonly referred to as 1/0 or "one ought". Type of wire depends on location & temperature, but in my common scenario I am using 1/0 THHN inside a 2" schedule 40 PVC conduit (3 - 1/0 wires plus a 4 ga bare ground) to run indoors, a distance of about 25 feet from my main panel to a sub for upstairs. I could go into more detail regarding outdoor, direct burial, grounding, aluminum wire, etc but would need more details.
I doubt if you can fit a 200 amp breaker into a 100 amp panel and it is illegal as the bus bars in a 100 amp panel are rated at 100 not 200 amps. The panel must be of the same capacity in amps as the main breaker that is installed in it. You can go smaller but not larger. The other problem is that a 200 amp service required three ought (000) wire. 000 copper wire with an insulation factor 90 degrees C is rated at 210 amps. Two ought (00) copper wire with an insulation factor of 60C is rated at 145 amps, 75C is rated at 175 amps and 90C is rated at 185 amps. Buy a complete house package that has the main breaker and all of the appliance breakers plus a few breakers for 15 amp circuits, all for one price that is cheaper that buying individual pieces.
AWG 2/0 copper.