I would consider a song that borrows a significant amount of the composition from a song of the franchise as a remix. Harmonic elements can be similar, but direct melodies/melodic motifs should be very minimal. A similar (or even the same) sound palette is completely fine. I think one way to look at it is: If your song can be considered an "alternate original theme" over a "remix" for a concept in the franchise, then it is considered ok! An example of "similar but not a remix" can be found in the final fantasy franchise, the battle theme in Final Fantasy 1 is very similar to the battle theme in Final Fantasy 4, but they are different enough to be their own unique themes
It depends mostly, I listened to your composition and I would consider it original enough to be its own thing! I would say I pay attention most to how exact the melodies when deciding. So something like route 1 in GSC I would consider a remix of route 1 RBY. It's hard to really draw a line for this so I'll tend to give benefit of the doubt, since the primary reason I made this rule was to incentivize the researching/analyzing part of imitation and to prevent situations where an artist might use a significant portion of another song without understanding why it sounds like Pokemon. In the future, I will try to see if I can come up with a more clear criteria for what I would count as a "remix"