He'll become available after completing the Cell Saga.
00. Testing Out
Skill acquired: All Clear
Simply reduce Cell's HP to around 20-25% to complete this quest.
01. Triplet Trouble
Skill acquired: Gravity Impact
In this battle, you have to eliminate three Cell Jrs. After taking out the two of them, a couple more will arrive to replace them. Just concentrate on taking them out and use evasive skills in case you get surrounded.
[in progress]
Okay just discovered 100% complete after you obtain his Ultimate Attack it is enhanced by the Z soul you don't have to spar with him after that if you don't want to though with the new Ultimate I wasted him with ease good luck and enjoy my fellow Xenoverse players!