Nothing is known about his appearance since he has yet to make an appearance.
On his sketch he is shown to have shoulder long hair, that appears to be slimey. He has a long jawline and a pointy chin. Toxic Chainsaw is very well built and muscular, he also has an outie belly botton.
Toxic Chainsaw is depicted as topless in the sketch. He wears baggy pants with skull-shaped kneepads and army boots.
Nothing is known about his personality. However, since he is a villain and seeing the reaction of someone who is knowledgeable about heroes and villains, it is most likely that he was ruthless and cruel, as he is still feared now.
Five years before the present age, Toxic Chainsaw fought against All Might. It is unknown what became of him afterward, but his name still lives on in infamy, as shown when Izuku Midoriya asks if he was the one who gave All Might the scar on his chest. All Might denies it was him though.
Nothing is known of Toxic Chainsaw's abilities, it is possible that he is quite powerful as Izuku considered the possibility that he could have been the one who injured All Might.
In the sketch he was shown to wield a chainsaw, befitting his name.