Will they be single character endings or specific tag team endings? Cuz I doubt Arcade mode is so short that it takes less than 2 hours to collect them all.
building a new version of his fighting machine from T4, Combot DX, you complete mini-games and trials and increase Combot's skills, which you can customize which skills from other fighters it can use as well as it's appearance [very Robo-Ky II-esque].
Yeah, I instantly thought of Robo-Ky II. This'll be a good time waster since I did love tinkering with RKII.
Edit: That, and Combot > Mokujin. :x