1 cup of soy milk contains 8 g protein
There are some fruits and veggies that have protein, but most are not significant sources. Split peas contain 16 g protein per serving, spinach has 13 and chickpeas have 8 g protein/serving. Avocados have 1 g protein per ounce. A medium peach has 2 g protein and 149 grams of dried figs have 5 g protein.
I love avocado smoothies, but avocados have a lot of calories, so you have to watch that. Peaches would be okay.
You can make a smoothie using soy milk, and sugar free chocolate pudding mix, but the only protein you'd get is from the soy milk.
Well - you have got to have a liquid - so the options are water, milk, or soy/almond/rice/coconut milk. Then you have to have some source of protein. Other than protein powder, you are pretty limited. You don't want to use raw egg. You could use nuts or peanut butter. Other sources of protein such as cooked meat or fish wouldn't be particularly appetizing in a smoothie. But there are a lot of options for protein powders, even vegan protein powders, and some of them are really tasty, so they are good options.