Oda Nobunaga:
Beat Story mode with all 12 starting characters.

Nobunaga Oda:
Beat Story mode with all 12 starting characters, and beat Nobunaga Oda in Vs. mode.

Gogandantess:
Beat Story mode with all 12 starting characters, and beat Gogandantess in Vs. mode.

Jujudormah Ran:
Beat Story mode twice as Jujudormah, and beat Jujudormah Ran in Vs. mode.

Miyamoto Musashi:
Beat Story mode as the normal soldier, and beat Miyamoto Musashi in Vs. mode.

Sasaki Kojirou:
Beat Story mode as Miyamoto Musashi.

Sasaki Kojirou:
Beat Story mode as Miyamoto Musashi, and beat Sasaki Kojirou in Vs. mode.

Magoichi Saiga:
Fight 200 times in Vs. mode and beat Magoichi Saiga in Vs. mode.

Mega Man EXE:
Beat Story mode as Samanosuke Akechi, and beat Megaman EXE in Vs. mode.

Mega Man EXE's Grand Style:
Reach level 2 as Mega Man EXE..

Mega Man EXE's Bug Style:
Reach level 3 as Mega Man EXE..

Musaido:
Reach level 2 as Three Eye.

Giramusaido:
Reach level 3 as Musaido.

Jaido:
Reach level 2 as Normal Genma or Sword Foot Light.

Marcellus Modify P:
Reach level 2 as Marcellus.

Marcellus Modify S:
Reach level 3 as Marcellus.

Zero:
Collect the Green, Blue, and Purple Crystals as Mega Man EXE.

Zero's Proto Form:
Reach level 2 as Zero.

Zero's Ultimate Form:
Reach level 3 as Zero.

Thanks to Revolution reader Musashi!