Theoretically, a 100% vegan diet should be able to provide you with all the vital proteins you need to maintain your health and even your muscle mass. However, it is quite difficult to put into practice because most vegetables lack all essential proteins, so you have to combine a lot of them to make sure you are covered. In other words, being a strict vegetarian and a bodybuilder is a pain in the ass. Personally, I wouldn’t waste my time. Veganism is an extreme viewpoint that should generally be avoided. It is entirely acceptable to avoid eating meat—I don’t often—but to completely eliminate all animal products, such as eggs, is simply going too far.
Furthermore, there is no proof that a vegan diet is healthier than, say, a Mediterranean diet that occasionally includes animal proteins. So instead of eating like a meat or animal food, try the Mediterranean diet.