Never played MVC2, was Vajra assist Stider common? I figured he'd be front man since Ouroboros costs 1 bar.
Vajra or the eagle was the assist in MvC2. But yes, MvC2 Strider sucks as an assist.
He can be put in second, but that's mostly so the first character can build the meter and then DHC into L1 Ouroboros with more meters to spare (one only need to look at Clockw0rk matches on Youtube to see that he does this with Sentinel/Strider).