There exist various websites on the internet where you can find "sample teams" for competitive play.
Here are some websites where sample teams for various formats are available.
1. Smogon Forums
Smogon forums is one of the most popular sites for competitive play and offers a very wide variety of sample teams. To find the sample teams, you go from the homepage to Smogon Metagames(for Gen 9) or Ruins of Alph(for Gens 1-8) and then click on the format or generation you want teams for. (OverUsed, UnderUsed, VGC, ADV etc.) Then you scroll down and find a pinned thread titled Sample Teams. The thread will have plenty of good teams of various types for your chosen format. (Use Ctrl + F if you have trouble finding it).
Link: https://www.smogon.com/forums/
2. Pokemon Perfect
You can find a lot of good gen 1-6 sample teams here. There's not as much variety as smogon, but it's still a good resource. Procedure for finding teams is the same as Smogon as well.
3. Pokemon Showdown!
Doing the /rfaq in most chatrooms will give links to various sample teams. You can also ask users for teams, but I can't vouch for their quality and don't recommend it.
Link: https://play.pokemonshowdown.com/
4. Smogon's discord servers
Most of these don't have sample teams listed, but you can request people for teams here. I can't vouch for their quality though, use at your own risk.
Link: https://www.smogon.com/forums/threads/smogon-discord-server-directory.3652546/
This list is not exahustive, there are many sources of teams I didn't mention, but what's here should be more than enough to get you started.
