An interesting team (and I don’t necessarily mean that in a bad way).
Each character has at least 1 assist that will greatly benefit the others (Shuma - Mystic Ray, MODOK - any, Arthur - Daggers or OTG flames), so there’s definitely some synergy there.
If you’re going for zoning, Arthur/Shuma/MODOK might work. Mystic Ray assist will keep them out of the sky while Barrier will protect you from a distance. However, this kind of zoning is weak to hyper combo punishes (such as Hawkeye’s Gimlet, Okami Shuffle, any beam hyper, etc). The only answer Arthur has to that is his level 3, which is a less than ideal solution to zoning problems. (Against something incredibly fast - such as Gimlet - you might try Arthur’s powerup hyper; it might have enough invulnerability frames to get through Gimlet’s active frames.)
Another reason to start Arthur as point is to gain access to a beefed up assist: with 2 bars, you can always use Arthur’s powerup hyper (it has invulnerability on most of it) and then DHC to your Middle character. Arthur’s assists gain a boost while he’s powered up, and the duration of his powerup doesn’t decrease while he’s off point.
If you’re more for getting in the opponent’s face, Shuma/MODOK/Arthur would probably work. Arthur’s daggers help close the distance, while MODOK’s Barrier assist helps you punish people trying to attack you. If Shuma falls, MODOK can utilize Arthur’s daggers for either zoning or rushdown purposes.
Admittedly, I am concerned about the team’s anchor position and DHC potential.
I don’t know if any of the characters in the team would make a good anchor. Does anybody else know about how good of an anchor these three characters are?
Also, I don’t believe there would be much trouble actually DHC’ing from one character to another. My concern is damage: none of the easily used hypers on the team seem to contribute a lot of damage (with the exception of MODOK’s beam hyper when fully powered up, and of course, level 3s).
On the other hand, since Shuma is there your Crossover Combinations should OTG. That’s always a plus.
Sorry I can’t offer much more input or insight on the team. They’re three characters that I’ve used before, but not very extensively (or even in the same team). I hope some of this helped, at least!