Basic tools such as picks and shovels. Though, nowadays, a lot of coal mining is done mechanically, with machines ripping out the coal if the coal face is thick enough.
To dig up coal
Linoone does not learn Dig by leveling up, instead it needs the TM to learn Dig.
No, Flygon cannot learn Dig by leveling up. You will need to use the TM to teach it Dig.
You will need to teach Hariyama by using the TM Dig. It cannot learn Dig by leveling up.
Vibrava cannot learn Dig by leveling up. You will need to teach it Dig by using its TM.
Pinsir cannot learn Dig by leveling up. You will need to give it the TM28 Dig to teach it.
The time to dig up iris is late summer when they are dormant.
I think you need a Pokemon with a specialy natural ability that will dig up items if you walk over them.
Depths of coal seams vary from place to place. The first coal mine in the US was in Midlothian VA, near Richmond. Coal was present on the surface- just pick it up. Later mines in that area were about 360 ft deep. Other mines are deeper- but much coal is still mined from the surface in high wall or long wall mining.
Of course. When you use it, you can't make more of it, you have to dig it up. And once you dig some up, you can't get any more of it out of the same place, you have to dig in a different place.
Zigzagoon wouldn't be able to learn Dig by leveling up. You will need to give it the TM Dig to teach Zigzagoon.
The coal mines dig up the coal from under the earth. The coal is then sold to whoever wants it. Some industries use coal for power. Coal-fired power stations are a huge buyer of coal. They burn the coal to heat water and use the steam to turn turbines which produce electricity. This electricity is then passed on to Energy Companies who sell the power to us.