Of the 13 main games excluding MMORPG's and sequels or spinoffs.
As I see it. Friendly dragons or dragon bosses gain it more points, as well as a large amount of common enemies that are dragons. So it could be a bit hard to decide how that balances out.
13: Final Fantasy XIII
There are no dragons in this game (unless you count the robot, Tiamat Eliminator). Even Bahamut is not a dragon here.
12: Final Fantasy XV
Wyverns are encountered as enemies in this game. These are the only dragons, as there are no dragon bosses, and although Bahamut is called "The Draconian", he is not a dragon in this game.
11: Final Fantasy X
Yuna gains Bahamut as one of her most powerful summons who can do more than the limit of 9999 damage. She and the rest of the party are forced to kill him to defeat Yu Yevon, the main villain.
Mika and/or Seymour also sends a wyrm, Evrae, after Tidus and his party as they go to crash Seymour's wedding to Yuna. They kill Evrae, who continues to exist as the unsent Evrae Altana, who encounters Tidus, Wakka, and Rikku underwater, but they kill it for good.
Two superbosses, Fafnir and Shinryu, can be fought at the Monster Arena.
Common dragon enemies (classified as Drake) include Vouivre, Lamashtu, Kusariqqu, Mushussu, and Nidhogg. (5 in total)
10: Final Fantasy VIII
During a play where Kiros is supposed to play a dragon, a real Ruby Dragon shows up, and Laguna defeats it in a minigame with the theme song that would later be used for the chase scene in One Ring to Rule Them All 2. He and Kiros defeat a second Ruby Dragon in an actual boss battle, then the place becomes infested with Ruby Dragons.
Bahamut is also fought (with an obscure way to get to him) to obtain as a GF (a Summon), and you also have to fight and kill Tiamat, one of Ultimecia's minions, in the final dungeon.
Blue Dragons, Hexadragons, and Ruby Dragons can be fought as a common enemy. (3 types total) It has fewer enemies than X, but I'd put it slightly higher.
9: Final Fantasy II
There is a Wyvern who is dying from when the Emperor poisoned their water, but gives you an egg to place into the lifespring, which hatches into a Wyvern that gives you a ride to the Emperor's Cyclone.
Also, four of the bosses you face are White Dragon (at Mysidian Tower), Green Dragon (at Cyclone, shortly before the first fight with the Emperor), Blue Dragon (at Jade Passage), and Red Dragon (also at Jade Passage). Also, one of Satan's generals (now working for the Emperor since he took over hell) is Tiamat.
Sea Dragons can be fought as common enemies inside Leviathan and on the ocean after Mysidian Tower. Them being the only common dragon enemy puts it lower than others despite there being two friendly dragons.
8: Final Fantasy VII
Three dragons are fought as bosses: Don Corneo's pet Rapps, Sephiroth's minion Red Dragon at Temple of the Ancients, and the two-headed dragon Schizo at Gaea's Cliff.
Bahamut Materia is obtained from killing Red Dragon, and can be used to summon the dragon king Bahamut. At Whirlwind Maze you get Neo Bahamut as a summon as well, and if you get all four Huge Materia, you can summon Bahamut ZERO.
Common dragon enemies include: Deenglow, Ark Dragon, Flapbeat, Dragon (Sephiroth slayed one in the rain), Velcher Task, Ancient Dragon, Lessaloploth, Blue Dragon, Dragon Rider, Wind Wing, Dark Dragon, and Dragon Zombie. (13 types total) Its higher level of dragon enemies rank it higher than II despite there being no friendly dragons besides the three summons.
7: Final Fantasy XII
Five dragons are fought as bosses: Tiamat, Elder Wyrm, Vinuskar, Tyrant, and Hydro. There are six marks (enemies you are hired to kill) who are dragons: Ring Wyrm, Wyvern Lord, Vyraal, Lindwyrm, Deathgaze, and the superboss Yiazmat.
Common dragon enemies include Wyvern, Bellwyvern, Gizamaluk, Twintania, Emperor Aevis, Dragon Aevis, Ash Wyrm, Aeronite, Cataract, Archaeoaevis, Shield Wyrm, Dheed, Aeros, and Skullash. (14 types total) Its higher level of dragon enemies rank it higher than VII, but lack of actual characters who are dragons (Bahamut being a fortress here rather than a summon) put it below others.
6: Final Fantasy
One of the Four Fiends, the Fiend of Wind, is the five-headed dragon Tiamat. She is the fourth Fiend to be fought and you kill her twice, the second time in the past, and played a part in making Garland – who created her – the overlord of evil that he is.
Also, the dragon king Bahamut asks you to bring him a Rat's Tail as proof of your courage, and powers you up when you do. There are friendly dragon NPC's in the Dragon Caves as well. A Blue Dragon can be fought almost as a miniboss (but every time you enter this area) at Mirage Tower.
Common enemies include Red Dragons, White Dragons, Dragon Zombies, Green Dragons, Wyverns, and Wyrms. (6 types total) Lower count of enemies and bosses than XII but Bahamut's large role and other friendly dragons put it higher, but barely.
5: Final Fantasy III
Bahamut attacks you at Dragon's Peak, forcing you to run from the battle that is meant to be unwinnable (you can win it somehow, but it means you can't defeat him later and obtain him as a summon). Later, when you're stronger, you can fight him at Bahamut's Lair and obtain him as a summon.
There is also a rampaging sea dragon named Nepto Dragon, whom you can't defeat if you encounter him, but when you return his soul (after going through a dungeon to retrieve it), he regains control of his body, gives you the Fang of Water, and goes back to sleep.
Two-Headed Dragon is fought as a boss, one of Cloud of Darkness's minions in the World of Darkness (though less significant in the long run than the first game's Tiamat), and in the Pixel Remaster is the only difficult boss.
Common dragon enemies include Sea Dragons, Dragons, Wyverns, Zombie Dragons, Bone Dragons, Green Dragons, and Red Dragons. (7 types total)
4: Final Fantasy IX
Kuja, the main villain, rides a Silver Dragon. Five Red Dragons fought as minibosses at Mount Gulug (three battles, the second and third against two each). Garland's Silver Dragon is fought as a boss. On entering Memoria you fight Nova Dragon, leader of the Silver Dragons, a whole flight of whom attacks on the way there but is taken out by the Lindblum Fleet and Tantalus. Tiamat is fought as a boss as well, as a multiheaded clone of Wind Guardian, a bloodthirsty dragon who is automatically killed by Vivi with Steiner's assistance.
Bahamut is summoned by secondary antagonist Brahne against Kuja, who controls Bahamut to kill Brahne. After being defeated by Alexander, Bahamut later becomes a Summon for Dagger.
Common enemies include Grand Dragons (powerful for the first time you can encounter them, and great for level grinding once you can kill them), Serpions, Ironites, Dracozombies, Worm Hydras, Shell Dragons, and Crystal Tiamats. (7 types total) The more dragons you kill, the stronger Freya's attack Dragon Crest becomes.
3: Final Fantasy IV
Rydia can summon Mist Dragon, who can do a decent amount of damage to enemies, and destroys Golbez's Shadow Dragon. Her mother's Mist Dragon is fought as the first boss, after being ordered to kill it by Cagnazzo. You can also defeat Bahamut, the God of Summons, and obtain him as a summon. Two of the bosses fought in the final dungeon are White Dragon and Dark Bahamut. Dark Elf also becomes Dark Dragon during the fight.
Common dragon enemies include Green Dragons, Yellow Dragons (very rare), Clockwork Dragons (also very rare), Thunder Dragons, and in the final dungeon, Silver Dragons, Gold Dragons, Bone Dragons, Blue Dragons, and Red Dragons. (9 types total)
2: Final Fantasy VI
There are eight Legendary Dragons that were sealed in the earth until Kefka breaks it apart when taking it over, thus releasing them. You get the Crusader magicite for killing all eight of them. They are:
Storm Dragon – Wind element, Mt. Zozo
Red Dragon – Fire element, Phoenix Cave
Ice Dragon – Ice element, Narshe Cliffs
Earth Dragon – Earth element, Opera House
Blue Dragon – Water element, Ancient Castle
Holy Dragon – Holy element, Cultists' Tower
Gold Dragon – Lightning element, Kefka's Tower
Skull Dragon – Poison element, Kefka's Tower
Bahamut is an esper here, but still a dragon at the same time, the dragon king. He was killed either by Kefka or Deathgaze; His magicite is obtained after killing Deathgaze, allowing you to summon him or learn Flare.
Common enemies include Lesser Lopros, Fossil Dragons, Wyverns, Zombie Dragons, Dragons, Platinum Dragons, Fafnir, Black Dragons, Chaos Dragons, Weredragons, Vector Lythos, Primeval Dragons, and Fiend Dragons. (13 types total)
The higher count of dragon enemies and dragon bosses (who have greater significance), and a dragon summon, put this game higher.
1: Final Fantasy V
King Tycoon (and, by extension, his daughter and playable character Princess Lenna) has a wind drake named Hiryu. You can ride him as your first airship, but there's not much use of him after getting the actual airship, and he sacrifices himself to drive Rift Demon Melusine out of Lenna.
Krile, granddaughter to playable character Galuf (and takes his place after his death), also has a wind drake, which helps her get you back to the castle, and a mission revolves around getting Dragon Grass to heal it so it won't die. Again it's a temporary airship, and unlike Hiryu, he survives.
There is also an enemy dragon, Archeoaevis, who guards the Earth Crystal for the Ronkans, a hostile civilization who worship the crystal, and is fought as a boss. Shield Dragons are also fought as a tough enemy, but with the right strategy they can be defeated for massive experience.
Common enemies besides Shield Dragons include Mini Dragons, Red Dragons, Wyverns, Mythril Dragons, Hydra, Ghidra, Istory Lythos, Zombie Dragons, Bone Dragons, Yellow Dragons, Wyrms, Blue Dragons, Magic Dragons, Archeosaurs, Great Dragons, Dragon Aevis, and Crystal Dragons. (18 types in total)
Between two friendly dragons playing a significant role, a dragon summon, another dragon boss, and the highest number of dragon enemy types, this game gets the highest spot of all Final Fantasy games.