Well, the "Doom Buster" super of his is based off of his Mega Man X3 Boss fight. Although he doesn't outright change his hand into a Buster when using it this time. I would have just called it the Sigma Buster, since it fits with the Mega Buster/X-Buster/Z-Saber naming convention. But that's minor. The eye-lasers are a mix of X4 and X8 attacks. The MMX8 one left a trail of fire behind if I'm not mistaken, but the beam is as thin as the X4 version. And his dash tackle has been in a bunch of games. Kind of neat it's in green, I was expecting purple since X5 colored it that way. And he has the counters that Ultron Sigma has.
Still, like Mega Man X, this is Sigma's first fighting game appearance as a playable character. And in each game, he has a lot of different moves, they are bound to add only so much in the first addition. But who knows, maybe in an update the two can get extra moves. That tends to happen between a lot of the Vs series. His level 3 does have wire frames of himself like X2. And it is a better Penace stare than Ghost Rider for some reason.
Sigma should have a lot of potential alt costumes given how many transformations he has. I would think that his X8 final form will be another costume, since I think the characters get at least 2
Black Panther seems cool too, definitely more like X-23 and Sabretooth than he is Wolverine. But people compare him to Logan as it is. Still, they could have implemented some things from recent cartoons like the Vibranium throwing knives and Staff, along with the typical claw stuff. But then he'd probably be compared to Gambit. There was also that time he was given the Black Knight's sword, which is probably the most notable thing that character has done in years.
I find 8 dollars a bit too pricey for a single character, even if they come with one costume. If the game adds some solid updates or was cheaper, I might consider getting it. But really, Capcom or Marvel screwed up with this. Not to mention Marvel throwing Capcom under the bus when it came to the X-Men characters, and then saying "Nah, they could have added them". I'm sure they could have, but what are the chances they were convinced not to?