Just put your other guy on defence only, this should keep you alive, do all the damage you can and when his magic point s reach close to 0 he'll sacrifice like 2,000 health, its basically an endurance test so put on shadow defence items and stuff to. If this doesnt work train up a few lvls and he'll die easy i bet.
The best option is to use the "Hydraulic" type. Here are the skills I used to kill him, Restore for healing it is a important skill so use it, Flash Freeze well i think everyone knows that stun is very important, Decimate, Impaire, Wreck, Vapour Cannon, Slam and the Avenger Form.
