Sigma attacks in a pattern in the game, so that we can defeat him. Sigma can fly and teleport, and he does not have to fly or teleport into the same place everytime now, does he?

Also, Seymour will need to actually find out where Sigma's weakspot is. Sometimes there are numerous spots on his armor, (hand, other body parts) which looks suspicious. (His chest armor has a shiny spot, there are sphere things on his shoulders, sometimes, for example.) It would take time before Seymour found out where to attack.

Bashing Sigma on the head wouldn't work most of the time, but rather you'll need to hit him in the face, or certain spot on his face. (For instance, the red ball on his forehead.)

Velguader is a really small dog (Well, a normal sized dog.), but he can deal out deadly damage from that small body of him. He is very dexterous and have speed, so taking him out won't be as easy as Anima blast him away.