The amount of each role you should have depends on the type of team you're trying to make.
I'll show you the recommended number of roles / tips for 3 main playstyles / teams: Offense, Stall, Balanced. (just in case if you want to try the other playstyles)
Scroll Down to see the Balanced team roles.
Remember to always have synergy / proper typing when making a team.
Offense
Sub playstyles include:
- Hyper Offense
- Bulky Offense
- Volt-turn
- Weather Offense
In Offense teams, you generally have 2 Wall Breakers, 1 Offensive Utility, 1 Lead, 1 Sweeper, and 1 Revenge Killer.
When making Hyper Offense teams, I generally follow one team building guide:
- Lead (ex: Crobat, Ambipom, Azelf)
- Wall breaker #1 (ex: Heatran, Banded Staraptor)
- Wall breaker #2 (ex: M-Charizard Y)
- Sweeper (ex: Haxorus, Dragonite)
- Revenge Killer / Scarfer (ex: Dugtrio)
- Utility / Hazard Removal that still hits hard (ex: Excadrill)
Bulky Offense follows the same plan, but it would use more bulky Pokemon; such examples include Dragonite, Garchomp, Conkeldurr, and more.
For Volt-Turn, my suggestion is to have slow U-turns and Volt-Switches to ensure a safe switch-in for the next Pokemon. A good core for Volt-turn is Rotom-Wash + Scizor. Basically, it should still follow the same plan as above, but also abuse U-turn and Volt-Switch.
Remember: Only 2 Pokemon with U-turn or Volt-Switch are needed to make a Volt-turn team.
Weather Offense is also a bit harder, especially since it has gotten nerfed heavily.
Here's my guide:
- Weather Starter (ex: Hippowdown, Politoed, Ninetails, Tyranitar, Abomasnow)
- Wall Breaker #1 (ex: M-Charizard Y)
- Abuser that Benefits from weather (ex: Kingdra has Swift Swim; Keldeo gets boost on its water-type moves under rain)
- Sweeper
- Revenge Killer (ex: Dugtrio)
- Utility / Hazard Removal (ex: Excadrill)
For Offense teams, you could also make certain roles as checks / counters to specific types / Pokemon. I suggest looking at the most common Pokemon as a tip for helping you making this, as this is a hard template to follow.
- 1 Bisharp switch-in
- 2 Mega-Lopunny checks
- 2 Azumarill checks
- 1 Lati@s switch-in
- 1 Landorus-Therian switch-in
- 2 Water Resists
- 1 Dragon Resist
- 1 Fairy Check
Obviously, you don't have that many Pokemon slots for that, so most of your Pokemon team are going to have to check as many roles off this list.
Remember: This list can change any time because the metagame is constantly changing. You'd have to keep up with the most commonly used Pokemon.
Stall
Here's what you should have on a stall team:
- Cleric / Heal Bell User (ex: Chansey)
- Status Absorbers (ex: Heatran, Skarmory)
- Hazard Setters (ex: Ferrothorn, Chesnaught, Skarmory)
- Defoggers (ex: Skarmory)
Usually, you should build Stall around a strong defensive core, such as the Regenerator core of Amoongus + Alomomola.
A Note on Stall Weather: The only viable weather that can pull off stall is hail. As always, you should have Abomasnow (a reliable Hail setter) and the infamous Stallrein set (Walrein with Ice Body + Substitute + Protect). Unfortunately, the number of turns that weather lasts has been significantly nerfed and Stall Weather wouldn't work as well as it did back in Gen V.
Balanced
Balanced teams often use good cores. Some examples include: Heatran + Azumarill + Lati@s or Mega Charizard Y + Gliscor + Tyranitar.
Usually a good Balanced team follows this structure:
- Special Sweeper
- Physical Sweeper
- Special Wall
- Physical Wall
- Lead
- Utility / Cleric
You could also make a Balanced team either more bulkier or more offensive, but not exactly Stall or Offense.
- You might do this by adding an extra Sweeper/ Wall Breaker , or an extra Wall / Tank.
Sources: Pokemon Usage Stats (by Smogon), Experience
Anyways, that's it! I hope I helped!