Sweet, thanks for taking the time to answer my questions.

1. The serial baudrate is 115200 by default.

2. Yes. The Arduino terminal will show the output.

3. Forget about the M5 register commands. This is NOT an ancient 8bit controller like the arduino AVR.
   Comparing the ATmega328p from Arduino Uno with ESP32 from M5Stack is like comparing a hammer with an fighter jet...
   Is a real hassle to deal with ESP32 registers and better just don't...
   Stick with the gpio access functions.

4. On M5Stack any pin (except the reset pin) can be used as ADC pin

If you want to use the oled display, the code should work as it is.
If you want to use the M5Stack LCD, you need to know some basic C/C++ (Arduino) programming to port the code.
First of all, you must switch from Adafruit_SSD1306 and Adafruit_GFX libraries to M5Stack library.

Is that where I replace the calls with the M5.Lcd. versions printed in the instruction leaflet?
And serial.begin needs to be replaced with M5.Serial0/2.begin(9600) ?

I can port this code for you to M5Stack but i think you should learn some arduino programming so you can write better code than this one...

Please don't. As you can see, I need to learn how to do this myself.
Is this any better? (well for the Arduino?)

**#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// Pin defines.
// int clkPin = A5;
// int sclPin = A4;
int throtPin = A3;
int pasPin = A2;
int spdPin = A1;
int motPin = 9;
// End of Pin defines.
// Variable Defines.
int th = '0';
int pas = '0';
int spd = '0';
int mot = '0';
//End of Variable defines.

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

void setup()
// put your setup code here, to run once:
{
pinMode(throtPin, INPUT);
pinMode(pasPin, INPUT);
pinMode(spdPin, INPUT);
pinMode(motPin, OUTPUT);
Serial.begin(9600); // Only for debugging.
// by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // initialize with the I2C addr 0x3D (for the 128x64)
// init done.
}

void loop() {
// put your main code here, to run repeatedly:

th = analogRead(throtPin);
pas = analogRead(pasPin);
spd = analogRead(spdPin);
display.clearDisplay();
display.setTextSize(2);
display.setTextColor(WHITE);
display.setCursor(20,0);
display.println(th);
display.setCursor(0,20);
display.println(pas);
display.display();
Serial.println(th); //Prints to Serial terminal
Serial.println(pas); //Prints to Serial terminal
Serial.println(spd); //Prints to Serial terminal**

A couple of questions?

1. How fast can the serial communicate on the M5?
2. Will the arduinos serial terminal show the outputs?
3. Where do I find the M5's register commands?
4. In the leaflet that came with the M5 it shows 2 ADC but the site shows more.
   Which is correct?

I can port this code for you to M5Stack but i think you should learn some arduino programming so you can write better code than this one...