Previous FF series character as a guest

[Orca]

Like the ff13-2 collesium?

This could be utilized to fight "dev-team" combinations, or things like face 3 people from FF8.

Something like that, i know theres a PvP arena coming but this would be nice to run alongside. I think thered need to be a rank system for unlocking more difficult fights, but generally i think one thing this game really needs is a source of content that provides accessible, difficult and interesting fights, without the complication of gathering 8 people. (solo, 4-man and 8-man divisions?) Since its also outside the story it pretty much provides the freedom to add whatever enemies they want. The biggest problem with adding cameos from other FF installments is the canon implications, and arenas tend to absolve that.

[Totorixiii]

Something like that, i know theres a PvP arena coming but this would be nice to run alongside. I think thered need to be a rank system for unlocking more difficult fights, but generally i think one thing this game really needs is a source of content that provides accessible, difficult and interesting fights, without the complication of gathering 8 people. (solo, 4-man and 8-man divisions?) Since its also outside the story it pretty much provides the freedom to add whatever enemies they want. The biggest problem with adding cameos from other FF installments is the canon implications, and arenas tend to absolve that.

Yes something like this even though Yoshida already said that the PVP will includes vs against his Dev-Team and including Wada as an event.
However, the idea behind this cameo appearance for PVP would be to sorta like climbing the floors in a tower and the further you reach, you can select multiple monster/characters from previous FF series.
So not neccessarily in a sense of climbing the tower but to basically move forward through the branch structures laid out. This would be a great additional ways to earn Achievements and Gils or Weapons/Armors.