Battle theme

Most Final Fantasy titles in the series have a normal battle theme, most often affiliated with a generic random battle encounter. A recurring feature in the earlier titles is that each battle theme starts almost identically, with the same two measures of eighth notes repeated in the bass clef twice before the main melody of the piece joins it in the treble clef in its third measure.

Final Fantasy
The normal battle theme of the first Final Fantasy is "Battle Scene". In the original Famicom release, this battle theme is played in both random encounters and boss battles. In subsequent releases, this is only played during random encounters. A remixed version can also be heard in Dissidia Final Fantasy, with the exclusion of the reccuring motif.

Final Fantasy II
Final Fantasy II's Battle Theme is called "Battle Scene 1". A remixed version can also be heard in Dissidia Final Fantasy.

Final Fantasy III
Once again the Battle Theme is titled "Battle 1".

Final Fantasy IV
Final Fantasy IV's Battle Theme is known as "Fight 1".

Final Fantasy V
Final Fantasy V's Battle Theme is known as "The Battle". A remixed version of this particular theme can also be heard in Dissidia Final Fantasy.

Final Fantasy VI
Final Fantasy VI's Battle Theme is known as "Battle Theme".

Final Fantasy VII
Final Fantasy VII's Battle Theme is known as "Fighting" or "Those Who Fight", and is the first battle theme that begins differently to the earlier titles (the bass does still play the motif however)

Crisis Core -Final Fantasy VII-
Crisis Core -Final Fantasy VII- has several different normal battle themes which play in different areas throughout the game, such as "Combat".

Final Fantasy VIII
Final Fantasy VIII's Battle Theme is known as "Don't Be Afraid", and has the distinction of being one of the few themes written for any title in the series in the 5/4 time signature. A remixed version can also be heard in Dissidia Final Fantasy.

Also of note is that Final Fantasy VIII essentially has a second normal Battle Theme, which plays during the dream sequences involving Laguna and his ragtag group of Galbadian Soldiers. During random encounters in this time compressed dream-world, "The Man with the Machine Gun" plays.

Final Fantasy IX
Final Fantasy IX's Battle Theme is known as "Battle 1". The introduction beckons back to that of the battle themes of titles I-VI. A remixed version can also be heard in Dissidia Final Fantasy.

Final Fantasy X
Final Fantasy X's Battle Theme is known as "Normal Battle". This is also available in Dissidia Final Fantasy, as "FFX-Battle Theme"

Final Fantasy X-2
Final Fantasy X-2's battle theme is called "YRP Battle 3".

Final Fantasy XI
Final Fantasy XI has several different battle themes. Which one plays depends on whether you are solo or in a group, whether you are in a dungeon, and which expansion you are playing.

Final Fantasy XII
Final Fantasy XII is the only game in the main series without a regular battle theme, as all battles occur seamlessly on the map.

Final Fantasy XIII
Final Fantasy XIII's battle theme is simply called 'Blinded By Light'.