Yea I totally agree with you Dodie, the pairings in this picture totally throw me for a loop. Sephiroth & Cloud then of all people Kefka & Terra. It is either a thing that they are working out or maybe they are just messing around with the idea of a tag-team fight or even special assist moves like you said Dodie where someone comes to your aid. Still very exciting to see.

One explanation for Terra fighting against Cloud:
SPOILER!!:
Maybe Kefka is able to control Terra's powers like he did in the first when he turned her against Onion Knight.