You're already starting off on the wrong foot if you're thinking of damage first with a 400x leader. Your Ideal alone will kill everything in A5 minus like 4 floors. You already mentioned how important you think Kanan is. If Kanan was Red/Light , would you immediately write her off because it's less damage as a light sub attribute? Would you disregard someone like Beach Tachibana who makes a perfect board and can boost you from 256x to 400x with the + combo count? Odin Dragon when you know you need an awoken bind clear? I've seen coop teams with Hao subs because it makes things easier for the teams as a whole. You get the point. Damage is not at the top of the list of importance and there are some light sub attribute cards that can deal the same, if not more damage than a main light attribute card that is forced on to the team. It's all fine and dandy to focus on strictly a light main attribute if you have an infinite box, which is what you're seeing from youtube players, but it doesn't sound like you do when you say how hard it is to make the team. Those card were just a farmable "extreme" example. I can almost promise you most people will make a team that deals more damage and is stronger all around when considering light sub attribute. If you want to stick to light main, that's great, but I don't think it's fair to call it insanely hard or a nightmare to make a team when you place your own restrictions on the team.