In any given fantasy series, there will be several different races and creatures that make up the playable characters as well as those that players interact with within the game. These races differ in physical appearance, backstory, and abilities. And it is important to note that there is definitely a spectrum when one is comparing the different races on strength and power.
Some races are softer companion types and others will fight (and defeat) anyone who crosses their path. Below is a ranking of a select number of races chosen from numerous games spanning the entire Final Fantasy series.
10 10. Human
The humans in the Final Fantasy world are entirely based upon their real-world counterpart. They maintain all of the same abilities and strengths that humans do; however, that does mean that they are weak. Though when juxtaposed with the races and creatures within the Final Fantasy world, they tend to come across as a little bland. They are not frail by any means but they do fall on the lower end of this list.
The Ancients are a mysterious race of beings within the Final Fantasy series who exist outside of society entirely. Though it is important to note that their race is known for having caused the Flood of Light before their self-exile. One of the last known Ancient beings survived a trip down a passage filled with lava. And if that is not indicative of deeply rooted power, then nothing is.
Though the fact that the only Viera present in the series are female and their physical likeness to mortal rabbits have caused some fans to write them off, the Viera have a deep capacity for power within them. The quickest way to explore their power is to expose them to Mist and allow the Mist Frenzy to sink in as, when afflicted, they have the ability to tear through metal and easily end the lives of the Humes around them. They also have enhanced physical abilities including enhanced senses that give them the leg up on those around them. It is important to never write off a character based on their perceive delicate qualities. Especially when those qualities are being written off as "weak" due to their perceived kindness or association with feminine things. The Viera are all of the proof one needs to see that even the most gentle creatures can break if pushed too far.
7 Black Mage
Being a weapon of war definitely earns a race a spot on a list ranking things by their capacity for strength and power. The Black Mages are a race limited to Final Fantasy IX who have the ability to cast Black Magic (one of the most powerful types of magic regardless of the fantasy series in which it is in contained.) They are ruled entire by their masters and will do whatever it takes to achieve their mission. Which can be rather brutal in execution.
Similar to the Guardian Force, the Eidolon are a race of summoned monsters that can be brought into battle in order to help those who call them. It is important to note that some of the Eidolon cannot be summoned until the person who summons them have bested them in battle (which earns their allegiance.) Their power ranking differs between each specific Eidolon but they are all quite considerable in ability regardless of if they are on the weaker end of the Eidolon power spectrum.
5 Guardian Force
The Guardian Force are a race of characters which can be summoned in select games in the Final Fantasy series. They are connected to the human that summons them and each and every Guardian Force has a select number of abilities and skills that they possess. Though their power does change depending on which Guardian Force is in question, they are still a considerable asset in battle situations.
The Kuluu are some of the most powerful beings in Final Fantasy lore based solely on their survival and endurance abilities. They were outcasted from their previous home and were forced to find a way to survive in the world. And that they did. They discovered a form of magic that could be used to summon avatars and eventually built cities of their own. But their abilities, those who originally outcasted them came back and did everything that they could to eliminate them.
Every fantasy series needs a dark cult in its lore. It's practically required. The Ascian are considered to be the personification of the feeling known as desire. Since their true forms are unknown, it is important to note that their appearances are a sort of disguise used to protect them in the mortal world and are easily recognizable by their dark robes. Ascian overlords are seriously overpowered and have the ability to possess living beings, travel between realms, and essentially regenerate.
The Padjal are seemingly ageless beings who were essentially created by The Elementals in order to be able to conjure at full power. Having the ability to wield magic to its full potential is an utterly powerful ability that should not be taken lightly. They are considered to have been "blessed by the forest" and are often likened to real-world holy figures due to the fact that they refer to each other as "brother" and "sister" as well as for their affinity towards white magic.
Though they are relatively unknown in the world at large, the Occuria are the most powerful race from the world of Ivalice. Though they can exist in a corporeal form, they can also appear in a ghost-like form or even make themselves entirely undetectable to anyone that they do not wish to be seen by. They can also merge with/possess other beings (which makes said creature far more powerful) and can only be ended while possessing a creature that can perish itself.