So, ruffians are cheap, but they seem to have even worse stats than goblins when it comes to fighting. So is there any hope winning a battle with ruffians, lead by sharkey. I guess the only pro is that ruffians do not need leaders so a game of lets say 800p would be quite insane - up to 148 ruffians without items with sharkey. So has anyone ever tried ruffians seriously or are they only meant for a small shire scenario? XD

Also, could ruffians work as an ally, does the rule still apply of making ruffian warbands without leaders?

Unfortunately Ruffians are Impossible Allies with every other army, which means they lose their army bonus (taking warbands without leaders). They have a range of extra Heroes in the Scouring of the Shire expansion which I think makes them better, but they are generally better suited to small games.