Well, as you can see from the ones in SHADEs 2 already, the EX characters are different versions with moveset changes and such. The EX characters usually use existing sprites, just to be clear, because if I have to make new sprites for them, I'd rather make a whole new character. That doesn't mean that I never make new sprites for them though. I just only do it when needed. As far as specifics, I can tell you the following about the ones I've made already, spoiler'd since it's a big wall of text:
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-EX Sabotage is very similar to the EX Sabotage in SHADEs 1. He's got an anti-air grab, a more powerful command grab, and the only super left intact is the Triple German Suplex, but even then it's a Double German/Powerbomb combo, although the execution and functionality is the same. His L3 is an homage to Geese/Rock's Raging Storm, called Seismic Storm.
-EX Exile is a more straight-forward version of Exile with roll commands rather than charges. He doesn't have the Spinal Distortion stance, but most of the moves you could do in it are now available all the time, like his life drain special and his L1 anti-air super. Most of his other specials have different properites, some small changes and some big.
-EX Ruckus has mostly different specials and a couple of different normals. Kind of like how EX Adamas is Adamas focusing less on his powers, EX Ruckus is Ruckus relying only on wrestling moves rather than any of his powers. His main command grapple is now The C-4, which is like a back-flipping suplex. He has a new special called Tornado Chop, where he spins towards his opponent and unleashes a knife-edge chop. You can hold down the P button to make him spin longer, but only on the HP version. He has a reworked Fighting Spirit super, that begins like the Tornado Chop, holding down the button delays the release, but once it connects it works just like the old super. His Asai DDT is now The Armani Shoe Exchange, which works similarly to the Asai DDT. With the Asai DDT, if the opponent was close, they got the DDT part, but if they were far away they just got hit by the moonsault. With the Armani Shoe Exchange, if they are close, they get hit with the attack, and if they're far, it connects like a grapple and does a Hurricanrana, so basically it's like a reverse version of the Asai DDT.
-EX Zenith is the only definite one I haven't worked on yet, though the plan is to just basically give him a different set of specials, such as a faster, more useful anti-air, a hopping overhead slash, a more traditional ninja projectile like kunai or shurikens, and some other changes. Still working out the details.
-EX Thirteen is also pretty much made already. He has the SHADEs 1 version of Relentless, which was basically the Iori dash-and-grab move. He also swaps Bed of Roses for a special move version of Bleeding Heart. Bleeding Heart is replaced with a new super, which is the only thing I have left to work on for him. He also gets From Hell back, which he lost in SHADEs 2.
-EX Kane Kelly, or Omega Kane, is the new final boss and is a direct response to some complaints I got that he was too easy. Kamekaze has toned down the usage of Negative Charge, which constantly left him wide open for punishment. This version of Kane has altered versions of his specials that give them more advantages, such as a faster descent on Comet Pressure, an extra attack on Avenging Angel that makes it very hard to punish, less recovery on a missed Negative Charge, and so on. He has a new L3 and a new DM. The new L3 is called In the Mouth of Madness, and involves The Entity unleashing an enormous beam of energy from its mouth. The new DM has no name yet and is a very SNK-ish full-screen super where he creates a ton of energy pillars. Think of an even bigger, longer lasting version of EX Adamas' Diamond Uprising DM. Don't worry, it's not too cheap, it doesn't do a ton of block damage and can be seen coming. But if it hits, it does decidedly boss-esque damage.
Anyway, as far as progress on the update goes, all that's really left to do is EX Zenith and the storyboard explaining Kane's transformation into Omega Kane. Kamekaze is working on finishing the main cast's AIs so that the arcade mode will have mor evaried fights. Dark Nation is done and might get a solo release soon.