You may have heard of this before, but if you haven't, keep reading. Eldegoss's signature ability Cotton Down lowers the speed of every Pokémon on the field (except for itself) by 1 when it is hit by an attack. With Malamar's Contrary, it gets a +1 in Speed instead. I came up with this a few days after the games came out, so I consider myself the "pioneer" of eldegoss and malamar memes.

Eldegoss @ Leftovers
Ability: Cotton Down
EVs: 252 HP / 4 SpA / 252 SpD
Calm Nature
IVs: 0 Atk
- Protect
- Charm/Cotton Guard
- Leech Seed
- Pollen Puff
Supportive Eldegoss set, nothing too out-of-the-ordinary.
-Protect because it's doubles, and it can stall out leech seed turns.
-Charm can be used on opponents or on Malamar to give +2 attack. Alternatively, Cotton Guard can be used to help soak up physical hits.
-Leech Seed helps chip down opponents while keeping Eldegoss healthy so it can keep activating Cotton Down.
-Pollen Puff is for if you get taunted, and for healing Malamar.

Malamar @ Aguav Berry
Ability: Contrary
EVs: 32 HP / 228 Atk / 248 Spe
Jolly Nature
IVs: 0 SpA
- Protect
- Brutal Swing/Knock Off
- Superpower
- Psycho Cut/other move
Again, a relatively basic Malamar set.
-Protect because it's doubles.
-Brutal Swing is here for the memes. It damages everyone, and activates Cotton Down (which is helpful when people see the strategy coming and choose to not target Eldegoss). Alternatively, just use Knock Off otherwise, since it's more reliable and you don't risk knocking out your teammate.
-Superpower because what Malamar doesn't use Superpower? It raises Attack and Defense each time you use it.
-Psycho Cut is strong STAB, but you could put any other move here as well.

Here are some battles showing the power of these 2. WARNING that I was very bad at this at first because I didn't know how Dynamax worked.

https://replay.pokemonshowdown.com/gen8doublesoubeta-1011361900 (this one had the added perk of hitting a King's Shield, which gave a +1 in Attack instead of a -1 in Attack.)

https://replay.pokemonshowdown.com/gen8doublesou-1014905107 (I'm just now realizing that this was a stall team... destroying stall teams is so satisfying)

https://replay.pokemonshowdown.com/gen8doublesou-1015664735 (turns out, you can't heal your teammate with Pollen Puff through Protect)

I have many other battles, but these were the ones where I played best. I had one battle where I was against a beat up and justified team (which I didn't realize at the time), but I played so atrociously that I can't post it here. I almost lost to a team that had a Krabby and a Tyrogue, it's very embarrassing.