Monotype joke of the day: there is no more of this, instead, enjoy MY PERSONAL type ranking.
1. Flying, they got all four of the genies, so they have now MULTIPLE electric immunities in Lando and Thunder, they got Goltres, a generally solid mon with a few set options (weakness policy agility or resto-chesto, to name a few) Esper Wing H-Braviary is a snowballing threat if you lack dark types due to tinted lens + scarf/specs, and there's plenty of other solid options available to use for flying
2. Dark, not to keep beating the long-dead mudsdale, but they have a lot of great options, Kingambit, Meowscarada, Overqwill, H-samo, Hoopa-U, Gren, Chien-Pao, A-Muk, Sable, Grimm, it's to the point where dark suffers from 6 mon syndrome.
3. Water, Greninja, Toxapex, Pelipper, Basculegion, Barraskewda, Walking Wake, Azum, and Volcanion (yay! A scald user!) Are amongst water's strongest options as of home, combined with the weaknesses water has being mediocre at best (grass and electric) and you have quite a strong type
4. Poison, Dire claw sneasler, need I say more? Jokes aside, mono-poison got some pretty strong options from home in the form of Hisuian-Qwilfish (and Overqwil) Glowking and Glowbro, A-Muk, and sneasler (good lord, sneasler.) alongside having a ridiculous amount of regenerator mons such as pex, amoongus, glowking and glowbro, pesky steel types? Salazzle can poison with corrosion or threaten them with stab flamethrower/fire blast, glimmora is always gonna be a decent option with free toxic spikes, and gengar blocks spins, one of the more important niches to have as a poison type, which relies on stalling out the opponent.
5. Steel, when home came out, Heatran returned once more to live rent free in the heads of fire mains, and hoodra came to almost entirely invalidate water, making it a firm option against bundle (if it were to return) while retaining most of what makes goodra good, and then there's gholdengo, whose usage shot up due to hazards making a return again, along with removal attempts. Iron treads is always gonna be a good hazard setter and rapid spinner due to high speed and reliable bulk, Corviknight is good as always with the ground immunity being more important with heatran on the team, and as if that wasn't enough, there's kingambit, no team with gambit is truly out of the match, Swords dance Sash sucker punch? Go ahead, vest + 4 attacks? Go for it? Sash reversal? Knock yourself out.
6. Dragon, Most Pseudos are part dragon type with the odd exception this gen being T-tar, along with that, most dragon types that are physical/mixed have access to D-Dance or S-Dance, (Garchomp, Salamence, Dragonite, Baxcaliber, Dragapult sometimes, Roaring Moon) and a fair few special attackers get nasty plot or just have high natural Sp. Atk (Hydregion, Regidrago, both Goodra forms, but Hoodra is better, Walking Wake)
7. Psychic, While Urshifu-S was running rampant on fighting, I would have ranked it a bit lower, but now that it's banned, psychic is now pretty high up on the list, and it has sharpness gallade, hatterene, Hisuian-Braviary, Espathra, Glow/Slow bro&king, Alolan-Raichu, and Hoopa-Unbound. Along with this, Psychic gets good removal of hazards, and even hazard returning in magic bounce hatterene or espeon, and Psychic has the ability to threaten poison, and help contribute to why fighting SUCKS.
8. Ghost, They have Gholdengo, Flutter Mane, and Spectrier, three good Pokémon due to their different ways of usage (maybe not the last two in terms of differences) along with that, houndstone has returned, albeit without the move that made it oppressive to deal with, and dragapult is always helpful against shed tail cyclizar/orthworm with infiltrator + dragon dance/specs/band, also, unaware skeledirge exists, so u can use wisp to cripple physical attackers, a very effective type held back by a dark weakness
9. Fairy, Crippled by losing the tapu quartet, fairy still somehow makes itself a type amongst the top half due to new things like Enamorus, Iron Valiant, and Flutter Mane combined with fairy being one of the best types in terms of match ups in terms of weaknesses and resistances.
10. Ground, STAB earthquake is always going to be nice, except when against flying types, but that's where rock type moves come in *stone miss* as for options, there's clodsire, (applaud him) Lando-I/Lando-T, Ursaluna, Tusk and Treads, Garchomp, Ting-Lu, Quagsire, Gastrodon, and Sandy Shocks if you're desperate for a ground/electric type for some reason, overall, a strong offensive type held back by a weakness to a top type (water)
11. Fire, with Volcanion, Fire has a water immunity and a decent way to best ground and rock types that isn't named scovillain, along with that, fire got heatran for the 5th generation in a row, and H-Arcanine is quite nice with no recoil rock head, flare blitz, double edge, and wild charge, and torkoal is always nice to have to set sun to trigger chlorophyll, boost fire type moves, and cripple water types (except walking wake) as for defensive options, unaware skeledirge just stops set up sweepers that can't threaten it and completely walls Iron defense Zamazenta. It must be said though that fire still loses points for the rocks weakness and no hazard removal other than rapid spin torkoal/coalossal or defog talonflame/oricorio
12. Electric, A solid type, has options like regieleki, zapdos, pawmot, rotom in general, thunder, magnezone, Electrodes, Iron hands, and Sandy Shocks, a great defensive type hindered by a lack of offense.
13. Bug, the type suffers from great mons having a HORRIBLE defensive typing in bug (weak to multiple common attacking types in fire, flying, and rock. While resisting grass, fighting, and ground, the same resistances as flying, which flying is immune to ground and resists bug as well) at least it threatens dark for super effective on all stabs, and has some pretty strong options in Scizor, Kleavor, Volcarona, Forretress, Lokix, Slither Wing, and I've even seen vivillion, venomoth, and frosmoth go wild at times due to quiver dancing.
14. Fighting, It's a highly offensive type with the ability to threaten mono-dark/steel for super effective damage, but both of those types have a ghost available (sableye/spiritomb for dark, gholdengo for steel) fighting also lacks many special attackers, which is problematic against a physical wall, and the loss of Urshifu isn't making things better due to single strike threatening psychic types that now run nigh unchecked against fighting.
15, Ice, saved from the bottom 3 due to Chien-Pao and Baxcaliber actually being good, most other ice types are slow and bulky, which is not good when paired with ice being like glass
16, Normal, Good defensive type, but Blissy lost toxic AND Soft-boiled got nerfed, there's no adaptability Porygon-Z or Eviolite Porygon-2, ditto is ditto as usual, and ursaluna, while good, isn't fast enough nor does it have a good defensive type, and H-Zoroark is definitely a good mon for screwing with your opponent's mind, not much else to be said other than the fact that it's on the lowest fifth of types.
17, Rock, A very offensive typing with mediocre defenses, but it benefits from sand with 1.5x special defense, and it has a good setter in tyranitar, a good setter of rocks and toxic spikes with glimmora, and H-Arcanine for strong recoil-free head smash nonsense, kleavor for keeping rocks in the event of a rapid spinner, garganacl for as"salt"ing the enemy with salt cure, and your last option can vary, however, it still doesn't have access to a flying type in gen 9, which would help against fighting and ground, nor a grass type to help with water and ground,
18. Grass, it just loses to most good types offensively in fire, poison, flying, ice, and bug, all decent offensive types, while resisting grass, ground, water, and electric, and it's resisted by fire, grass, flying, bug, poison, dragon, and steel
Please note, this is MY PERSONAL ranking, feel free to disagree.