It was a PSX-only feature to play as the sub-bosses in Tekken 1. The sub-bosses in the arcade version actually have less moves than the ones in the PSX version as they were not meant to be playable in the arcade version.

I managed to hack the arcade Tekken 1 and play as the sub-bosses and sometimes the game crashed and thats how I noticed they had less moves and outfits too.

> I never had much of a chance to play the original Tekken in arcades, and playing
> the arcade version in Tekken 5 made me wonder: Was it ever possible to play as
> the sub-bosses in the original Tekken arcade, or was that a PSX-only feature?
>