Concept Name: Special Wall
Description: A Pokémon that can check or counter powerful Special Attackers
Justification: The current Special walls in the metagame, being Blissey, Dunsparce, Milotic, and Jellicent (though it's phys def sets are more common), plus Special tanks in Hariyama and Snorlax, are fine, but I'd say there's less good or splashable options for Special Walls than physical walls and plus, a certain special attacker by the name of Ledian is able to muscle past these would be checks sans Blissey and Snorlax thanks to Magic Guard ignoring Toxic and Tail Glow's speedy setup. Thus, another viable option, especially one that can cripple or KO Ledian, would be much appreciated since more options makes teambuilding easier.
Concept Name: Rapid Spin User
Description: A Pokémon that can effectively remove Spikes with Rapid Spin
Justification: There are a lot of good Spikers in the metagame right now, with Skarmory, Roselia, Dunsparce, Forretress, AND Cloyster (and after the move slate, maybe Omastar and Cacturne as well), while conversely, every viable spinner, of which there are a good few as well, has huge flaws that make it harder to remove hazards than it is to set them up, usually due to being easily spinblocked by the increased number of viable Ghosts (Forretress, Cloyster, Claydol, Donphan), easy to KO (Hitmonlee, Cloyster), or would rather be doing something else (Jumpluff, Hitmonlee, Cryogonal), with the only not particularly suffering from any of these problems being Starmie, though that's not to say it doesn't suffer from these problems to a lesser degree. Thus, another option for a Rapid Spinner that can address one or more of the limitations that Rapid Spinners currently have (without having to go and add Defog or something)
Concept Name: Weather Disruptor
Description: A Pokémon that can remove weather from the field or otherwise make it a non-factor for a short period of time
Justification: With perma-weather, the meta is defined by Tyranitar's Sand and Delibird/Abomasnow's Hail. While a few Pokemon can ignore weather for themselves, like the Magic Guard and Overcoat users or Cloud Nine Jumpluff, none of them have a way to support their teammates or mess with the opposing team. The only things that can really do this right now are Rain Dance users like Ludicolo and Kingdra and Dugtrio's ability to trap Tyranitar, though Delibird and Abomasnow make these strategies a lot weaker. Thus, something that can support itself and its teammates by removing weather can help de-centralize weather. However, if this concept were to win, we would have to be super careful about it, since something that shuts down weather completely would completely warp the metagame around itself, so it's ability to disrupt weather should be temporary
Concept Name: Viable Poison-type
Description: A Pokémon that uses the strengths of the Poison-type to find a niche in the metagame
Justification: Despite being a meta where Toxic is super common, Poison-types are actually extremely rare in the meta, with the only viable ones being Gengar, Toxicroak (who nobody knows how viable it is yet), and Roselia, plus the extremely niche Venusaur and Minun. While it's easy to see why this is, with Rock and Ground-types being everywhere, Skarmory and other Steel-types being everywhere, and most Poison-types simply having bad stats or just happening to be outclassed by Venusaur/Roselia, Poison-types have a lot to offer in the metagame namely a Toxic immunity without needing to use the limited Magic Guard options, a strong STAB move in Sludge Bomb that hits common Grass-types hard and only two weakness that, while common, can be easily covered for.