Hello there, which research role were you referring to? Are you asking about the Knowledge Team (KT) role?
Generally speaking, they are looking for strong candidates they believe are a good fit! This shouldn’t stop you from applying for the generalist consulting role if you’re not specifically interested in the KT role. Additionally, BCG typically does not proactively reach out for generalist roles unless the position is fairly senior (Principal+), where they want someone with certain expertise.