Basilisx is cold, ruthless, and bloodthirsty. He is more than willing to use underhanded tactics to achieve victory. Despite this, he has shown a small degree of honor, as he refused to use his infamous petrification stare against Mario despite freely admitting he could easily have done so and then used his claws to shred apart his petrified body, although it should be noted he mostly chose this route so he could fully satiate his desire for vengeance against the plumber. He has a strong vendetta against Mario, who he accused of murdering his best friend along with countless members of the Koopa Troop. He also seems to have a bit of a temper, as shown when he petrified one of his own men after they had difficulty activating the Doom Kanon. 

In the original animation, Basilisx's voice was used of 1st Form Cell from Dragon Ball Z. It doesn't have to be 1.1 but try your best to get close to that: https://www.youtube.com/watch?v=3bkmfxLnVxQ