Okay, but isn't Kevin going to have a character arc in this, or isn't it more of a stand-alone?
With some thought, I don't believe Kevin quite needs a character arc. This movie serves multiple purposes, but a way to emotional or mentally transform Kevin is not one of them. The movie acts as a good time for viewers, a domino to set up a cinematic universe, proof our character is the right woman for the job, and an experiment with side characters.
Because it would be cool if, after what happened to him with the omnitrix (which, how did he become normal again in the main series' canon that first time?), he became reluctant to use his powers to their full extent? (Or a all?) That would also make Rojo a more credible threat.
For the first point, I agree that Kevin's change back to normal is something of a mystery, but I feel we should save this for a latter date. Moreover, as we choose to keep his power with a narrower focus than
[] Go with both. After all, why wouldn't you want to make Kevin more powerful?
both any kind of reluctance feels misplaced. If Kevin only has access to matter absorption than why would he ever feel
bad about using it? As for Rojo, we don't need to make her a physical powerhouse, nor give her extra power( in the abstract) to make her a credible threat. We can make her a problem through other means.
We can have it so, despite Kevin's past connections to the criminal underworld, Rojo has and is developing stronger ties. Kevin's been out of the game and on the social outs with criminal elements. All that do-goodening with Ben and Gwen, but more importantly The Plumbers, mean criminal elements are hesitant to associate with Kevin. In a contest, between whether criminals and outlaws want to associate with Kevin vs his old partner Argit, the criminals trust Kevin more; however, Kevin doesn't interact as much as he used. Unlike Argit who is steeped in the criminal culture, but who keeps burning contacts for being a metaphorical two-faced rat. Sure, Kevin has some support with giving people like the Forever Knights and Highbred an ass-kicking, but there's always that question of: Is today the day Kevin Levin wears a wire and ruins
my personal racket for the forces of legality? Kevin could surely win over these criminal elements with his charisma from Rojo, but is the cost actually worth the effort?
Or, Rojo can have an easier time escalating violence, but Kevin requires he has materials on hand. Sure, he can always fallback on the ever reliable stone, steel and concrete, but Rojo's basic alien weaponry wears down human
building material fairly easy. Worst come to worst, Rojo spends the extra cash, favor or influence to get something heavier or more exotic to use. Whereas Kevin can't quite do that. Back in Alien Force, I believe Gwen tried to set up Kevin with material marbles in a bag, but the problem with that is there, wasn't enough material to cover his whole body. There's also the issue that some materials are much more expensive/rare to find. Or Kevin's truly mellowed out, so he doesn't go for violence as easily as he once did. He wants to be a better person, and better people do not flip a switch to be homicidal.