Obviously this is a very rough prototype so I won't be too critical but the biggest problems I see here are the lack of telegraphing and the combat moving too rapidly.
I can't tell when or which enemy is going to attack, and they attack extremely quickly. Realtime combat can work but I think the enemies have to give you some breathing room, and knowing what the enemy timers are is important to keep the player informed for decision making, and also to make it so the enemies dont just feel like they are randomly hurting you and not obeying any rules.
Related, it's impossible to know which character you have selected, which makes the telegraphing even more confusing. I'm also not sure what the point of a character who has no skills when they are out of energy is. If she can't attack she should at least have some kind of weaker free ability so she remains relevant.
The visual style is nice but I'm not a huge fan of the shading model on the characters, feels more appropriate to have some kind of stepped shader or a cartoony phong effect. Stealing TF2's shader model would work nicely with these designs imo.
The environment is a little bit drab, I think more contrast on characters could help them pop. Perhaps lighting them separately to the room lighting so their colors show up better?
Overall there's a foundation here but it needs a lot of work to get off the ground.
P.S. bug report: the tall guy pathed outside the map and was no longer able to receive commands even though his charge meter filled.