Rurouni Kenshin: Ishin Gekitouhen [PSX]

Zanza's sword:
Hold Select when choosing Zanza on the character select screen. Zanza's Zanbato sword will be available for use.

Fight as Kaoru:
Beat the game in story mode or vs computer mode to choose Kaoru as one of the fighters.

Fight as Saito Hajime:
Beat the game on the hard difficulty setting to play as Saito Hajime. You will also be able to view all the FMV sequences in the game.

Aoshi: Low Spin Kick:
Press Down, Kick + Guard. Aoshi will do a spin low kick and send his opponent kissing the ground.

Kenshin: 360 Low Slash:
Press Forward, Forward, Punch + Kick. Kenshin will do a 360 degree Low Slash instead of the 360 Mid Slash.

Easy win:
Set Punch and Guard to only one button, to increase the success rate. In battle, just press Back repeatedly, and when your opponent comes near, press the Punch/Guard button. Repeat as needed.