Awww... you stopped mentioning past FF homages before getting to the most important one...
Terra's Guardians are the Crystal Guardians from the original Final Fantasy! I loved that little detail, especially since I played FFIX before FF1 and therefore found this out after the fact.
Also, you reminded me that there's a piece of music that plays at only the part where the teams are confronting the guardians that I remember really loving but haven't heard in forever. Now I can't even remember the name of it.
EDIT: Nevermind, Found it!
Some of my favorite tracks in video games are these "Put the Plan into Action" themes, such as Stage is Set from FF8 or Judgment Day from FF7.
EDIT 2: Just realized a lot of Successive Battles can be considered a preamble to Skirmish of the Silver Dragons. Lots of similarities.
Number puns seem to be pretty common in Japan, that's why March 9 is Miku Day/Giving Day.