For biking shorts you'll want fabric that is durable, stretchable and moisture-wicking. You'll have less chaffing on those longer rides and these short designs are styled and made to withstand rough terrains.
Biking jerseys and tops should be light weight fabric, keeping you comfortable while wicking away moisture for the best breathability. There are many great styles to choose from.
Keep your hands comfortable and safe while on the MTB trails. Gloves should protect and help you grip the handlebars nicely. Find various styles here.
MTB specific socks can help keep your feet dry, comfortable and free from blisters. Important for long bike rides.
Keeping yourself hydrated and fueled up well is super important when you're exerting yourself and burning energy while biking. Running out of water and not carrying snacks is never good! I highly recommend always having more with you than you think you'll need.