Okay, after reacquainting myself on Viktor's feats, I am of the opinion that he cannot beat Rakan. Speed-wise they are more or less equivelant, Jack Rakan had the physical strength edge by a good margin, and his durability and destructive capacity are not on par with Rakan's by any means. After Rakan takes out Viktor and Kazuki, there's really no one else who is a threat to him, Viktor or Kazuki could quite easily solo their own verses (Shit, Viktor did).
Rakan clears through Busou Renkin rather easily. He can casually send out mountain busting ki beams, is fast enough to react to a lightning timer in combat, can throw punches just as fast as said lighting timer, can spam swords that can cleave through warships, and has a soul cutter in the Zanmaken Ni No Tachi. Even if you take away his Pactio, he still has plenty of power to handle a great deal of opposition. Even Victor and Kazuki aren't going to do too much to him. Rakan has plenty of ways to take them and the rest out without breaking a sweat.