I usually play with Vikings. Sometimes when I play against Chinese, the opponent already has Zen masters when I arrive at his base. He kills off the units that I send against him and whenever he reaches my base he has about 3 Zen masters, which is enough to finish me off. Ive tried several things. It obviously doesnt matter if I start out with berserks or axe throwers, because he kills them both without getting damage. So I could start out with thunderbolts, but it usuallay takes to long to get it, or the mana is expired too early to kill enough zen masters.

Any new strategies or any suggestions for changes in my strategies?

Try building as many units as you can - mostly axethrowers and some beserkers and research and use charge as fast and effective(the more units gathered in the cloud the more damage it does on the impact) as you can.

I can usually counterattack a Zen rush with Aztecs and Vikings , but i find it really hard to do with Chinese. I think next time someone does Zen rush, i may try to build a Buddha as soon as possible to cut off how far they can move.

With aztec you can trap them. Thats what I always do and then kill them without taking damage. If I see a group of them I drop poison and kill them before I have to worry about it. Alternatively, you can get towers and kill them off easily. With chinese use terra cotta soldiers. Chances are they will pick up one of them instead of your regular units and they will kill zen master pretty quickly. If they do pick up one of yours, just use the invincibility spell to drop him. I never really play with vikings, but Im sure you can use lightning to zap them, and alternatively you can use the towers with axe throwers to stop them.