Garchomp @ Focus Sash
Jolly Nature 
Ability: Rough Skin
EVs: 252 Atk / 252 Spe / 6 SpD
-Outrage
-Swords Dance
-Earthquake
-Iron Head
Usually Swords Dance if safe enough and then just sweep until it dies or the enemy team does. Sometimes switching it out to use later if you can get something else out safe enough. My plan was to use my old Generation 4 singles team for this. But some changes had to be made due to move availability. For Garchomp, that means Iron Head instead of Fire Fang. Iron Head is mostly for Fairy types or when you know you need to select a different move next turn, Outrage is often stronger than it. Rough Skin is quite useful for when something uses a contact move on Garchomp, it’s also this Garchomp's only way of hurting Shedinja. Which appears in Classic mode and at least one trainer in Master Class. 

Suicune @ Leftovers
Bold Nature
Ability: Pressure
EVs: 252 HP / 252 Def / 6 Spe
-Scald
-Ice Beam
-Calm Mind
-Rest
With Suicune you can more or less just Calm Mind and Rest spam and then sweep.  Ice beam being helpful for hitting Pokémon with a Water type immunity and anything that it hits super effectively as well of course. Rest is also useful for removing other status conditions and with Pressure as well, Suicune is quite good at PP stalling, but not as much as the older towers because NPCs have PP Maxed Pokémon here. Scald has a chance to burn as well, which can be quite useful if you’re lucky.  You will need to transfer a Suicune in from an older game (not virtual console) for the Pressure ability. Inner Focus is still usable though if you have to use a Sinnoh Suicune. I got my first few Ribbon Masters done with Inner Focus Suicune. 

Scizor @ Sitrus Berry
Ability: Technician
EVs: 252 HP / 252 Atk / 6 Spe
Adamant Nature
-X-Scissor
-Bullet Punch
-SD
-Thief
This here is my Metagross. The loss of Iron Head as well as some of the changes to the type chart sometime after Generation 4 make it a less appealing option here and everyone else was using Scizor at the time, so I went with that.  Bullet Punch is decent damage priority move, X-Scissor for bug STAB since Bug Bite is long gone, Swords Dance for extra damage like Garchomp and Thief because Shedinja exists and the Dark coverage/item removal can be nice, because Knock Off is also unavailable for Scizor now. It can be useful to train the team in another game and then do the moves in Brilliant Diamond/Shining Pearl.