I always recommend a "food first" approach to nutrition and encourage my clients to use supplements only when they struggle to meet their needs through their diet. On these occasions, I recommend topping up the nourishment you receive from food with a few key vitamin supplements and I have linked some of my favourites below. Protein powders can also be used to support performance and recovery in those who find it difficult to eat sufficient protein. I have linked a good all-rounder protein product for both plant-based and non-plant-based diet as a good place to start but there are a great many products available.
Important: it is always recommended to obtain required nutrients from food and supplements should not be used in place of a healthy, balanced diet. If you are an athlete and you decide to use supplements, always check the product batch number using the following link to minimise risk of banned substances https://sport.wetestyoutrust.com/. Medications can be checked using https://www.globaldro.com/uk/search. It is your responsibility alone to ensure you are training and competing clean.