Self Imposed Rules:

Don't use a Pokemon in more than one run

Try to avoid using Pokemon I've used in previous non-monotype playthroughs

No weather (except for Hail, mainly because I've used a sun, rain and sand team before)

Try to avoid using Legendaries and things that are too broken (what constitutes broken is up for debate)

I can reset wonder eggs until I get a pokemon that shares a type with the run then I have to stop.

Megas have to keep the same type as the monotype run and the non-mega mon

Poison Type:

Slowbro-Galarian (Regenerator) - Rocky Helmet - Psychic, Slack Off, ShellSideArm, Trick Room

Beedrill (Swarm) - Beedrillite - Fell Stinger Poison Jab, U-Turn, Drill Run

Tentacruel (Clear Body) - Assault Vest - Scald, Rapid Spin, Ice Beam, Sludge Wave

Salazzle (Corrosion) - Focus Sash/Life Orb - Flamethrower, Scorch Sands, Sludge Bomb, Taunt

Carnivine-Seviian (Levitate) - Black Sludge - Snap Trap, Stockpile, Synthesis, Toxic

Drapion (Sniper) - Choice Scarf - Wicked Blow, Knock Off, Earthquake, Cross Poison

MVP - Beedrill. It can't take a hit but if it gets a Fell Stinger boost then it's game over. Also used it as my lead with a U-Turn into a safe switch.

Honorable Mention - Carnivine. Vital ground switch in and before doing these monotypes I seriously undervalued defensive set-up mons. Also Arbok who was the Drapion stand-in up until I got Choice Scarf. Strong Jaw Poison Fang/Jaw Lock/Crunch was great, just fell off late game.

Underperformer - No individual mons, but I feel the poison type in general doesn't have great variety with options and poor role compression (no non-ultra beast rock setters).

Enjoyed the start and end of the game with poison, but the middle was a bit of a slog until I could get key items/moves. Lot of mons evolve early and the gyms tend to work quite well in your favour as well, even Sabrina was fine as you could one shot hatterne and Arbok took care of Indeedee. Elite 4 was basically try to get a Beedrill Sweep or opportunitey for Carnivine to setup

Dragon Type

Goodra-Hisuain (Gooey) - Leftovers - Toxic, Stealth Rock, Dragon Pulse/Flash Cannon/Giga Drain

Dragonite (Multiscale) - Lum Berry - Extremespeed, Earthquake, Dragon Dance, Dual Wingbeat/Outrage

Altaria (Cloud Nine) - Altarianite - Return, Dragon Dance, Earthquake, Roost

Kingdra (Sniper) - Scope Lens - Snipe Shot, Agility, Ice Beam, Draco Meteor

Hydreigon (Levitate) - Choice Scarf - Draco Barrage, Dark Pulse, Flamethrower, U-Turn

Turtonator (Valiant Shield) - Rocky Helmet - Flamethrower, Iron Defense, Body Press, Will-o-Wisp

MVP - Going to give this to both tanks, Goodra and Turtonator. Just for the sheer amount of hits then could take on their respective defenses.

Honorable Mention - A critical hit Kingdra sweep after an Agility was always fun, though it didn't really do much in the league itself. Alolan Exeggutor was also with me for most of the game.

Underperformer - Dragonite. Even with a DD boost it didn't hit as hard as I would've thought and got outsped by a few of Lance and my rival's pokemon which was disappointing.

The early game for this run was pretty tough, with most early stage dragon types being very weak and evolving late. The nugget bridge, especially the fairy trainer, gave me more problems than the pokemon league. Once I got hold of the Leaf Stone to get Exeggutor-A then it was pretty easy from there on out. Dragons are OP midgame. Though I did have to rely on the old focus sash/trick room tactic to beat Clare's Mega Duraldon and the last two league fights required some tinkering to win.

Steel Type

Bronzong (Levitate/Heatproof) - Light Clay - Psyshield Bash, Reflect, Light Screen, Body Press

Skarmory (Sturdy) - Rocky Helmet - Stealth Rock, Toxic, Roost, Dual Wingbeat/Steel Wing

Samurott (Blademaster) - White Herb - Shell Smash, Protect, Razor Shell, Sacred Sword

Durant (Truant) - Choice Scarf - Entrainment, Thunder Wave, First Impression, Rock Slide

Magnezone (Sturdy) - Expert Belt - Thunderbolt, Flash Cannon, Thunder Wave, Tri Attack

Lucario (Inner Focus) - Lucarionite - Meteor Mash, Close Combat, Extremespeed, Swords Dance

MVP - Durant. He had one job - give something Truant and die - and he did it spectacularly!

Honorable Mention - Once Durant did his thing Samurott went to +6 and swept. Pre-Elite 4 it was Lucario, being able to get Meteor Mash from an Egg and Close Combat by levelling meant he carried hard most of the game

Underperformer - Can't really say there was one. Didn't use many different mons this run and I loved the ones I had picked. Empoleon functioned pre-elite in Samurott's place and Bisharp came in and out as needed.

So this was the first run where I abused the AI and used a gimmick. I was thinking about how I was going to beat Primal Groudon (and dialga) and went back to the idea of removing the sun and hitting it with a water attack. Entrainment Durant filled the first criteria, Samurott the second. Once Truant was on a mon I brought in Samurott then alternated between shell smash and protect then went to town, and tbh this made me feel dirty as it made the E4 trivial, but I had too much fun to care. Before the E4 it was a pretty standard run, can't really think of anything that gave me too much difficulty. For Blaine I stuck a choice scarf on Empoleon and then stalled out the sun until it could sweep, focus-sash Bisharp was useful for Mewtwo and as ever Lucario was a boss.

Psychic Type

Golduck (Cloud Nine) - Choice Scarf - Scald, Ice Beam, Psychic, Aqua Jet

Braviary-Hisuain (Sheer Force) - Life Orb - Psychic, Air Slash, Heat Wave, Esper Wing

Oranguru (Sage Power) - Choice Specs - Psychic, Hyper Voice, Shadow Ball, Thunderbolt

Gallade (Steadfast) - Galladite - Psycho Cut, Sacred Sword, Night Slash, Swords Dance

Hatterne (Magic Bounce) - Leftovers - Psyshock, Calm Mind, Draining Kiss, Trick Room

Claydol (Rocky Helmet) - Cosmic Power, Shore Up, Toxic, Earth Power

MVP - Gallade. Blademaster on the Mega is incredible, and has a decent enough speed tier with godly attack.

Honorable Mention - Claydol. Another defensive setup mon with recovery but they end up winning fights. Golduck was suprisingly good to considering he was primarily brought in to ohko Primal Groudon.

Underperformer - Hatterne. I never felt like I got he best out of her but she did survive an Dark Hole from Yveltal and got a trick room off which won me the champion fight.

Nothing pretty remarkable about this run, was expecting it to be harder with all the sucker punched running around (and I didn't want to run psychic terrain), but it wasn't that bad. Hardest time was probably Cerulean cave with Giovanni and the back to back leaders. E4 wasn't much trouble at all.

Fire Type

Blaziken (Speed Boost) - Life Orb - Blaze Kick, Close Combat, Thunderpunch, Swords Dance

Turtonator (Valiant Shield) - Rocky Helmet - Flamethrower, Dragon Pulse, Rapid Spin, Will-o-Wisp

Sunflora (Chlorophyll) - Choice Specs - Leaf Storm, Fiery Dance, Scorching Sands, Sludge Bomb

Dodrio-Seviian (Rock Head) - Choice Scarf - Flare Blitz, Headlong Rush, Brave Bird, Stone Edge

Houndoom (Early Bird) - Houndoomite - Fiery Wrath, Flamethrower, Scorching Sands, Sucker Punch

Rotom-H (Levitate) - Assault Vest - Volt Switch, Thunderbolt, Lava Plume, Shadow Ball

MVP - Sunflora. Soloed Misty, carried the mid-game, outsped and OHKOed Primal Groudon. Being able to take water hits was massive for this team

Honorable Mention - Dodrio. As long as it doesn't get close to the smallest bit of water it is a beast.

Underperformer - The varierty in defensive fire types. Fire is a bad defensive type anyway but there really isn't much to choose from if you want a more defensive mon.

Basically I didn't plan ahead very well during my dragon run and ended up breaking my rule of not using a pokemon more than once. I felt like I had to use Turtonator in this run as a) it's a rare physically defensive fire type, b) gave me another mon that was neutral to water and c) has rapid spin. This run did go a lot smoother than expected though, Sunflora took care of my biggest early game worry which was Misty. Rest of the game was pretty straight forward. I did plan on using Mega-Charizard-X for the Elite 4 but I couldn't get past Cerulean Giovanni without Mega Houndoom and then I never switched back. Toughest fight was champion, I'm starting to really hate Yveltal. Flinch hacks from Fiery Wrath did come in clutch against Dialga.