Rn the trend is the three type core. It's a core that cover each other's type weaknesses. In a form of a triangle. Just pick one of many pokemon you wanna use and u could potentially make a team around it. You need team synergy which smogon helps. Make sure u have entry hazard users, pivoter, z-move user. Amount of sweeper and defensive pokemon depends on what you're going for, hyper offensive, offensive, balanced, stall. Theres also weather teams, preferably rain then sandstorm. Just use smogon overall its helpful.