So I have a question that I have been playing around with for the last number of years, whilst playing the Final Fantasy games.

Who is the strongest Summons/Aeons/Eidolons/GF in the entire Final Fantasy universe?

Now I apologise straight away if this isn't the place to ask this question but after spending some time looking for an answer to my question, I found that it might be easier to just ask on this forum. Now the condition of the answer are as follows;

A single variation of Summons/Aeons/Eidolons/Guardian Force etc. will suffice e.g


And also if there was a hierarchy system in place, What way would you structure it?