To dream of a mech suit may reflect a need to use something to your advantage to defend yourself emotionally. Using something to make yourself stronger than you are on your own. Taking advantage of an opportunity to make yourself more impenetrable to opposition or defensive against criticism.
Negatively, a mech suit may reflect a dependency on using an ability or resource to make yourself look stronger than you really are. A fear of confronting a conflict without an advantage you can control. Knowing that “underneath it all” you are not as strong as you project yourself to be.
Example: A young man dreamed of wearing a mech suit while chasing an armored car. In waking life he was stubbornly telling all his friends and family that he had to live his life on his own without them as he left his hometown to look for better financial opportunities. He used his need to be on his own as an excuse to look strong while excluding people because he didn’t want to look weak.