I think your buying into the "realism is brown" fad a little too much

The new purple guy looks awesome. I would advise you to go into little color details for the rest too. Give them a color identity besides their anatomy and pose identities.
Some suggestions might be:
- Thick suspenders for the big guy
- Other color for the blond guy's sweater around his waist
The other two have clear color identities now with the purple and red, so that's fine.
I think the remake might be the time to find a better pose for the blond guy too, somehow the action line is very similar to the fire dude. Maybe make his body face the other way while his face remains looking right (does that make sense?)