in a style in which is to show a MK9 player how to play this game, via differences/similarities. Also, I feel this game has less damaging comboes or am I wrong compared to MK9. Also, a tier lis?
Differences from mk is you need to know your options when you knock down your opponent and decide to pressure them, which jumpin attacks do you have with a good hitbox that can either crossover or just do a normal jump. Make sure you know what kind of knockdowns you need to guarantee or give you a good chance of a 50/50 on knockdown since blocking is now pressing the opposite side of where your opponent attacks like in traditional 2d fighting games.
In this game there aren't a lot of standing/special anti airs. If you don't want to air to air them or focus your whole game on just anti airing like I do pick a character who has good anti air, some of these are wonder woman, aquaman, deathstroke, green lantern, grundy.
Blowing up strings works different in this game, when you study a matchup make sure what strings you can backdash out of because you can whiff punish them after a backdash.
Dashing and walking works different, after you dash you can't immediately do an attack like in MK, figure out the spacing of your character...
These are just things off the top of my head right now, I would recommend you playing aquaman or wonderwoman, since I feel like during neutral they can play the most mk9 like footsies and both are at least top 10, imo top 5.