i like how red hood's hud overrides pretty much everything except the gadgets on the bottom left, and his detective mode "neutralized" state instead of unconscious i dislike the overuse of guns i like red hood's unique style of play
Brutes do take damage, they just have a lot of HP. You may have been very close to killing him with guns. Shield, stun, and knife brutes are also not three separate enemy types at all, but one type that can switch between three different modes. Evade him for long enough and he'll give up and try a different weapon type, which he was literally three frames away from doing before you interrupted him
I really wish we could actually play as Batman's allies on Free Roam in Arkham Knight (Robin, Nightwing, Red Hood, Batgirl, Catwoman and even Harley Quinn). If it was possible, the game would be a good version of Gotham Knights. But, unfortunately, it is not possible. I mean, you can do it with mods, but some features just wouldn't work quite well.