Iroh is from Avatar: The Last Airbender.
Iroh is a firebender, which means he has the ability to shoot and manipulate fire to a certain extent. This power draws from sunlight, so he and all other firebenders lose it during a solar eclipse. Firebending is also supercharged during Sozin's comet, which happens once every hundred years in the Avatar universe. It's unclear if this is an effect caused by all comets, and most noticeably by Sozin's, or if this comet, in particular, has some significance. There is no observable difference between firebending ability during night and day, nor does cloud cover appear to affect it.
Some skilled firebenders also have the rare ability to shoot lightning. It is unclear if this ability is genetic, or merely extremely difficult, although it would seem to be the latter. We have never seen Iroh, in particular, generate lightning, although he implies that he has the ability to, and avoids it because he knows how dangerous it is.
Iroh is an extremely skilled firebender, to the point that he is confirmed to have invented at least one firebending technique, and there is at least one more that is only seen being used by him and certain other extremely powerful firebenders (which is implied to be a sort of trademark of his, being the source of his nickname "The Dragon of the West"). These are, respectively, the ability to receive lightning fired at him and fire it in a new direction without harm coming to him, and the ability to shoot fire from his mouth without moving his arms or legs.
Battle Experience Edit
Iroh was a high ranking general in the fire nation for many years. He is known for commanding the fire nation army during the six hundred day siege of Ba Sing Se, a famously impenetrable city. After six hundred days, he managed to breach the outer wall, but his son died at that point, and he abandoned the siege in his grief.
What this means for debates is that he has experience with large battles, and he has experience commanding others.