I think Joe might be the lowest character. He just lacks damage and pressure. His zoning is his best quality and the fact that he relies so much on zoning and couple of characters like Clark and Mr. Karate just annihilate Fireball Zoners I think Joe is kinda' SOL.
Joe is a huge wild card because of his stun combo. I think I could place him low even with the stun combo but with high execution players he may be a very silly character.
As for Leona she does not seem limited to me. Her only limitations are 1. meterless damage, which is moot since she is a thrive on meter character and she's going to be 2nd or 3rd, and 2. she has to spend meter for a reversal. With meter, simple confirm into level 2 does enough damage, and her hd combos hurt a lot.
Her biggest strengths are 1. her normals are ridiculous. Kula-ish cr.B, low profile sweep, big st.D, fast low C, big and good angle jump CD, awesome stand CD, vertical jump D with a huge hitbox. 2. She is the only character in the game with an unseeable 50/50 with vertical jump D. Every other character with command overheads or command grabs, you at least have a chance to react or try and alt guard a throw/hit or jump out of overhead/throw. Leona you just guess. D slash is 0 on block so that allows her to set up cr.B/jump D 50/50 from that, very annoying.
But I will say she can never be in the absolute highest ranking because of the backdash change to console. It offers a pretty safe solution to her mixup, and if you actually block the high mixup it's unsafe.
Speaking of Leona I really hope Cheng Long is playing this game and using her. I think someone with high execution and talent can make her crazy...she's really the only character in this game that terrifies me.
anyway heres a list i made so everyone can flame me or w/e. also i dont use the graph its just a normal vertical list, horizontal doesnt mean anything:
link