...? I don't understand this sentence. I can't parse what you're saying the level of complexity for Rivals and Brawlhalla are, or the level of complexity you expect for Icons. Brawlhalla and Rivals are already at two very different levels of depth/execution/complexity.
I've played Brawlhalla for all of 6 hours and already feel like I've grasped most of its system, any further work is honing my spacing and then just mindgames. It's fun and the relatively simple fundamentals let you get to the mindgames faster (but it doesn't have a tutorial to teach grav-cancels :/ ), but I already know how to play Skullgirls yet also think I have much more to still learn than I do in Brawlhalla.
I have 13 hours in Rivals and learning how to successfully dodge is very opaque, I don't really understand the benefits of wavedash, I can kinda parry and have basic three-hit combos. So I'm way more interested in watching high-level play.