What do you do with juicer pulp?
Does it still contain any flavor to make something out of it?
How about vitamins?
This depends on the type of juicer and how well it extracts the juice from the fruit. The best juicers leave a relatively flavourless pulp (which is, however, very high in fiber). If you're curious about the flavour, try tasting it! (I've heard of the pulp being used to make muffins, but other flavouring agents are definitely required).
I am not sure about the vitamins, I am willing to guess that they exist primarily suspended within liquid (water for the water-soluble vitamins, oil for the fat-soluble ones) and a good juicer will leave only trace amounts of either type in the pulp.
We have a twin-screw masticating juicer (an older Angel juicer) and have found that when we make carrot juice, the pulp works well in carrot bread or carrot muffins. It's quite dry and it's finely shredded and ready to be mixed in to the bread.
I have no evidence to support this, but based on my understanding, it should be a great source of fiber, it definitely has "some" flavor and color (in many cases enough), no juicer is perfect so there are some remaining vitamins and other goodies that you expect from that fruit or veg in the first place that could be released (to be absorbed) by cooking.
So you need to try! and report back so that we can get inspiration!