Divine Speculation and Heavenly Apex Artillery

My Little Pony fan fiction relatively often compares characters like Celestia, Luna, Cadance or Discord to gods.
I personally think that while this is a curious notion, it is not unjustified.
First, we have to ask one thing:

What is a god?

Surprise, surprise, there isn't a clear and simple answer. Hence I will now try and categorize the most common types of god.
Tier I:
The classic god emperor. A normal person, apart from the fact that he is an absolute ruler and commonly viewed as either a god or of divine heritage.

Tier II:
The superpowered physical god. It is usually immortal or at least hard to kill and possesses great supernatural powers like throwing lightning or rising celestial bodies. This is probably the most common type as it it used in many mythologies (Greek, Roman, Norse, Egyptian, you name it).

Tier III:
The fantasy setting deity. It is not physically present, but grants its priests and followers different blessings. It is immortal, but often depends on worship as a power source.

Tier IV
The omnipotent, omniscient, absolute, immortal god. The most known example is the abrahamic God worshipped by Jews, Christians and Muslims.

Now to the ponies.

Due to obvious reasons, Tiers III and IV can be ruled out beforehand for any character in MLP.

Celestia and Luna definitely fulfil the requirements for Tier I. They reign over Equestria and, although not stated explicitly, have a godlike status, as evidenced by figures of speech like "Thank Celestia! ", "As Celestia is my witness" or "In the name of Celestia".
However, I would rather place them at Tier II, because they are not only more than a thousand years old but also responsible for rising sun and moon. Of course we don't now how immortal they are, but full immortality isn't a requisite for Tier II.
On a side note, while Celestia was defeated by Queen Chrysalis, the latter didn't manage this on her own, but with the help of Shining Armor's love. I will expand on that at a later point.
The Princesses are powerful, old and physically present, making them a shining example for Tier II.

Discord seems to be able to do everything the Princesses can, and more. He is known to take off body parts and to transform on a regular basis.
Tier II. Nuff said.

Now, about Cadance, I'm sorry to disappoint all fans of her, but what is given us of her is just not sufficient for Tier II.
First, she's too young to have displayed any immortality as she was a teenager when Twilight was a filly.
Second, she has not displayed any power above that of Twilight's or Shining Armor's.
Her love-bringing powers seem to be as effective and morally dubious as the "Want It Need It"-spell.
The force field of love and light she conjures up to defend the Crystal Empire is impressive, but definitely not unheard of.
While she did defeat the changeling army, it wasn't her power that did it. You could argue that Shining Armor and Cadance did this with their combined power, I would rather interpret what is given such that it was the power of their love that defeated the changelings, the same power that was abused by the changeling queen to defeat Princess Celestia.
It is a common theme in fantasy that "true love" itself holds great magical power and is able to break and prevent curses, bring the dead back or, in this case, expel an army of vampires. My Little Pony seems to follow this policy.
Thus I would conclude that even though the power of the love between her and her husband is beyond doubt, she herself has not displayed any power that is to be called godlike. Thus she cannot claim to belong to Tier II, yet.

In conclusion, both our beloved Royal Sisters as well as our favourite spirit of chaos have what it takes to be called a god.