Number nine. PSP remake that included the original game in all its forms and an enhanced port of its sequel as unlockables.
Number eight. A lot of games in my top 50 already listed are in this franchise. This game is Super.
Number seven. This game is an NES game and the original version of the previous number. Number eight is actually a remake and not a numbered game. Should help answering both.
Number six. The original is the best and the second one is all around good, the others are good because of the gameplay alone. This RPG series is worse with each new installment. The first two games were ported to Playstation consoles and while the first Playstation game isn't that bad, the worst problem with the game is the backgrounds in combat are prerendered 3D instead of 3D, the Playstation versions are worse. The second game is a good game that's well known for it being a very poor port to one of the Playstation consoles having graphical bugs, audio bugs, and lag everywhere.
I'll jump ahead and also give the hint for number five as well.
Number five. Don't use Google for this, that'd be way too easy, but after finding this out I've never once forgotten it. The hint is 6:10:50.