Not really. Bullying is House-neutral; Slytherin and Gryffindor both bully each other as well as random other students. Note the heavy non-Slytherin presence at the last bully battle, and note that James Potter was in Gryffindor. And Quirrelmort, who was (for the sake of argument) in Slytherin, spoke of how much he once hated bullies.
Not really. Bullying is House-neutral; Slytherin and Gryffindor both bully each other as well as random other students. Note the heavy non-Slytherin presence at the last bully battle, and note that James Potter was in Gryffindor. And Quirrelmort, who was (for the sake of argument) in Slytherin, spoke of how much he once hated bullies.