Type B personalities allow Type A personalities to bully them and then wonder how to say no?
I am naturally a Type B personality myself but when you are surrounded by Type A people all day it is crucial that you learn basic defensive instincts. It is no different than when a bully singled you out when you were in school. Your first and immediate reaction is to have more confidence than the bully and no fear.
Confidence
Whether it is a school yard bully or pushy PM, have supreme confidence in your self and you will exude an aura of strength. People sense confidence and strength and it completely changes their interactions with you. When they talk with you, look at them in the eyes, don't avert your gaze or look at your feet. Speak candidly and fluently, do not stutter or stammer, do not use ummm, and uhhh when talking. A person with confidence and resolve knows how to articulate EXACTLY what they want to say and how to say it.
No Fear
When lowering your confidence level does not work, another tactic they will use is to instill Fear in you to lower your confidence back down to a level that makes you easier to control. This can be extremely hard to deal with, especially for myself as I suffer from Generalized Anxiety disorder which is an obstacle to overcoming negative emotions.
Fear is NEVER rational, an important survival instinct for sure and a healthy amount will keep you out of trouble, but most fear can be harmful. Who wants to just survive? For somebody who needs to be on top, who needs to lead the pack, fear will hold you back as the only way to overcome it is to have a do or die attitude.
When you feel the fear of negative consequences, attack it immediately with rational thought. Dispell it, prove to your mind how ridiculous your emotional reaction is, remind yourself of your own strengths and ignore the disapproval of others.
Social pressure can be the biggest, fear of disapproval, fear of being judged. I dispell this by reminding myself of my own just actions and by attacking the notion that the person passing judgement has no right to do so. A little bit of arrogance or narcissism helps to deal with this.
Analyze weakness and the power of Pity
We are all human beings and deeply flawed. These flaws manifest into inherent weakness we hold. Some are better at hiding them than others, but a trained eye can spot them and use them to better understand the people you deal with professionally and otherwise throughout your life. It isn't a battle, so it is wrong to think of it this way, because when dealing with people you always want to win without having to resort to an altercation. When this happens, nobody wins. A good read that COMPLETELY changed my frame of mind for the better is:
The Art of War
Weakness can be exploited, the PM coming at you guns hot, what motivates him? Pleasure? Not likely a sadist. Greed, possibly he wants to get the product out the door faster to impress the client or secure a nice bonus. Fear, thats probably it. The client is not happy and is on the phone placing all the blame on him/her. They simply do not have the resources to address the problems they face. They are scared. Really scared. Who can save me? Nobody. Then who can I exploit? The other PM's are in a more dire situation than myself, and I am not about to go to them and start a fight. That one developer, the quiet guy who is easy to get along with. If I can convince him...
Now that you understand their motivations you know their weakness, fear is a bigger motivator than greed because fear is more primal. How can you use this to your advantage?
In conversation I start talking about the clients and the problems with them. I start bringing up the bigger picture. If I can get the PM to open up and trust me then it is harder for that person to do something unfair to me. I use emotionally led arguments, talk about the fear, this lowers defenses and they are more likely to have a friendly moment with you. This is easy to do if you approach an oppoenents fear with pity, but you need to be careful not to be patronizing.
Pity can have a powerful effect on people, powerful enough to motivate you to post a question about your problems anonymously on a Q&A site, more or less to advertise your troubles and evoke a pity response from others in supportive comments or advice.
Fear and pity can help you turn the converstation into a dialogue, and not a bully session. In a dialogue, you go back and forth until the two of you come to a mutually beneficial arrangement that leaves both of you walking away with a good emotional response from the encounter.
I am unfortunately focused on completing another high priority task at the moment, which will take me about the rest of the week, and I understand and sympathize with your lack of resources to address your problems at the moment, but you will be my number 1 priority next week.
So ultimately...
Just say no
This simple two letter word is the most powerful in the English language. Much more so than yes as any married couple will tell you, it takes two people to say yes in a relationship, but it only takes one to say NO and stop something immediately.
It all starts with No and it need not be any more complicated than that.