Here, Spike was trained to be a Royal Guard, resulting in him knowing how to fight and did a lot of good with that. Would Canon Spike have any fighting skill like that? Who would train him if he had gotten to know how to fight? Flash Sentry? Shining Armor? Rainbow Dash? Garble? Smolder? Ember? Torch?
Simply put, If Spike were to have fighting Skill, who trains him? And what sort of fighting skills would he have? Offence, defence or a balance between the 2?