Gunpla is the best
I know at first you would think you need all these fancey materials in order to paint, but all you really need is basic paint that can go on plastic and a brush. this is a tecnic we call hand brushing use of your hands to paint models. thier are many types of paint you can use from applewood to citidel paint the paint you use does matter on what you want not just in color but in how log it lasts and how much are you willing to spend.
other supplies may incude execto knife, clipers/nippers, sandpapper, plastic cement/glue that can adhear with plastic, paint palets,mix containers, and stensils.
Yes these items are not necessary unless required buy the kit instructions but they are nice comodity to carry for your long term use.
