It is easily done with Yuri by himself by using the Tension skills to have Yuri in infinite Overlimit loops.
What is absolutely needed is: High Tension, Hyper Tension and Ultimate Tension. These skills allow Yuri to automatically activate his own personal Overlimit (not based on the teams Overlimit gauge) every time he lands enough hits in a consecutive combo. So basically you can use the normal attack chain, followed up by a Base skill with multiple hits (e.g. Shining Fang), followed up by an Arcane Arte or Altered Arte (e.g. Dragon Swarm, Shining Dragon Swarm, Shining Fang Drop, etc...) and once you activate High Tension after twenty-eight hits you'll be in Overlimit Level One so you can repeat the process until you activate Hyper Tension, and so forth. You can use this to carry you to infinite numbers.
This video:
here, gives some decent instructions and example of using Yuri for infinite combo-ing. The only thing he failed to mention is that you will likely need to use the Skill Minimum Damage to make sure you only do 1 damage to an enemy with any attack. That way the enemy won't die before you combo string reaches and/or exceeds 100 hits.
If you need any more specific details on the skills he uses, and what they do, or even how to get them, let me know and I'll try to help further.