There is a lot of styles that are designed around being the 'best' or else they would fail pretty poorly against any skilled fighter.
Some styles do have a reputation as being pretty lethal though, Bak Mei was said to have been a system designed to kill Shaolin rebels, as a result its full of nerve and pressure point strikes which can often get around lower level iron shirt.
Tai Shing of Tai Shing Pek Kwar was an offical style of the emporers gaurd at one point. It was designed to be brutal and fast but most importantly different. At those times people had seen a lot of styles and the element of suprise became a big issue. Bagua has also been used by the royal gaurd and so had to be able to go head to head with other master martial artists. Praying mantis was designed to beat the orginal northen shaolin curriculam. Tai Chi is another art invented to combat higher grade external arts like shaolin.
Wether or not they will actualy do that job depends largely on the practioner. Most better styles have some tricks up there sleeve.
"I have heard that Leopard Claw will destroy/crack Golden Bell 9 out of 10 times."
- Iron shirt i would say no probs but goldbell is much trickyer, one way that can work wonders is to grab and area with a tiger claw pull out and that hit with a pheonix before there muscle retracts, this way you have dislodged what your striking from the body of the opponent. Sounds complicated and it is How to actualy DO it though, ahh thats another story hehe i hope something doesnt strike me down for saying all that
Up and down, forward and backward, left and right, its all the same. All of this is done with the mind, not externaly.
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Shaped dragon and looking monkey, sitting tiger and turning eagle.
"I wonder how they would do against jon's no-tension fu. I bet they'd do REALLY WELL."
- Huang Kai Vun