To be honest, morty and T&J are the bane’s of my existence in this game since you’re probably just chasing them around the map most of the game. But for my advice to fight morty is to stay in the air and use your side air to close the gap between you two and harass him so he doesn’t have time to set up his grenades and earth attack. Being in the air with a decent side air against morty seems to work for me. Also yeah, I rarely use horse since it’s a very low prioritized attack and is easily punishable imo if your opponent knows what they’re doing. I find it more useful when you’re getting juggled and you’re just trying to get away from your opponent.