Different Pokemon Setups
Preferably a fast and somewhat bulky pokemon that uses toxic then either whirlwinds or roars it's opponent away in order to use toxic on the next opponent. The idea is to poison as many members of the opposing team as possible in order to soften them up for the rest of your team. This can also be used with other status conditions if you are looking to hinder your enemy in a different way
The Toxic Fang
This is definately my prefered method of taking out bulky pokemon. You get a pokemon that can learn super fang and teach them both superfang and toxic and when your opponent sends out a bulky pokemon just poison it on turn one, use super fang on turn to and just stall from there. It's not the most heavily used strategy but it is very useful especially if you put it on a bulkier pokemon
Fast Uber beater
If you are having trouble with a garchomp, salamence, or some other fast pokemon that does crazy damage then there is a very easy solution. Get a pokemon that can learn both endeavor and quick attack and equip it with a focus sash. On the first turn against that pokemon use endeavor. The pokemon should knock you down to 1hp with the help of the focus sash. Your endeavor will then drop them down to 1hp. Then just use quick attack to drop their 1hp and you have KOed the pokemon that was giving you trouble. This can even be used to defeat level 100s with much lower level pokemon. You can also teach this pokemon flail so it can further benefit from its 1hp
The Sunny Beamer
This isn't my favorite strategy but for many people it is the greatest invention since sliced bread. The strategy is pretty straight forward. Use sunny day to make solar beam not need to charge and then just keep spamming solar beam. This can be very effective but when a lot of players see sunny day in play they will send out a fire type which can ruin this strategy.
This strategy requires only a single move on your pokemon and can wreak havoc very easily. Teach a pokemon a move with a high base power of its own type, such as blast burn on charizard, or flail on a normal type, and just use this attack on any pokemon that doesn't resist it. Most things will be one hit KOed while very bulky pokemon may take 2-3 hits but that is fairly rare.
This role is best suited for a milotic. Get double team on your pokemon, give it an item that heals it every turn, use a move that heals the pokemon every turn, and then use any move you want in the fourth slot. Toxic normally works very well with this set. Your pokemon will almost never be hit and when it is it will heal itself over time. This strategy is usually very infuriating for the enemy once the double teams are set up.
Get a bulky pokemon and teach it either mirror coat or counter. When you come up against a pokemon that you can counter then use either counter or mirror coat on them and one shot them while your pokemon only loses around half of its health. This pokemon can also be accompanied by leftovers or a chesto berry and rest
Endure and Flail/Reversal
Pretty simple strategy. Just get a fast pokemon that can get flail or reversable and preferably get STAB on it and use endure when you think your pokemon might get KOed and then spam flail or reversal. Endure is sometimes preferable to a focus sash because it allows you to hold a lum berry which is important when running this set as a status affliction will completely cripple the pokemon.
The Type Coverer
A pokemon that is intended to cover as many different types as possible. Usually a pokemon with all the elemental punches or fangs. This pokemon usually doesn't one shot many pokemon because it doesn't normally get STAB but it can still be an effective 2 shotter