Can I use r Ultron to attack using an Energy Explosion while adjacent to e Taskmaster (Enhancement + mimicing Shield Team ability) and boost his initial target and splash damage to 3? Assuming I have a Shield agent on my team...

Yes, this is completely legal and can be done.

Ouch! i was originally going to correct the math that Taskmaster would only add 1 to the attack by giving him an action to use the mimic'd Shield team. I thought for a second that the 3rd point came from Ultron also being a shield mimic until i re-read that Taskmaster was on Enhancement.