~vs~
Isa is as seen in Sin and Punishment: Star Successor, in his Stage 7 form. He functions as if Kachi is fused with him, and cannot unfuse with or be separated from her. In addition, he can use both Isa and Kachi shooting modes and charge shots.
Selvaria is as seen in Valkyria Chronicles, with access to her Valkyrur lance and shield as well as her Rhum machine gun. She cannot use her Valkyrur Flame self destruct power.
Terry Bogard is as seen in his younger, more traditional form from the King of Fighters and Fatal Fury series.
Bill Rizer is as he appears in the Contra series, in his playable Neo Contra incarnation. He has access to Laser and Crash from Contra 4.
Orochi is as seen in the King of Fighters series with all his moves except for Enhanced Soul Steal. He also has all the moves Mizuchi uses in Neo Geo Battle Coliseum. There are no invincibility frames or gameplay mechanic-y moves however.
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boring and mundane signature
Now with more bold! Less Italics due to bold