Attackers per type

For one, I wish I had the dust and candy to be able to do this. Very well-done!

No Salamence for dragon type? I know it performs similar than Dragonite but I'd be tempted to throw one for style points and variety.

Other random things I'd consider:
Maybe A-Exeggutor in place of one of the regulars for grass?
BB Charizard in place of a Flareon or two?
Piloswine for the ice team? Mamoswine's introduction would make an easy substitution there. For that matter I'd drop in an Articuno there too.
If you have an extra Mewtwo you could run psychic moves in place of an Alakazam.

The rest I have no strong feelings for. That Pikachu better have Surf.

Your teams look pretty solid.
You werent kidding when you said steel needed help, I guess the obvious choice is to remove those 2 Aggrons with whatever good steel pokemon we get in Gen IV.
Also why not Psychic Mewtwos? Dust and RC can be spend somewhere else though if thats the reason it ok

I've considered it because it seems kind of fun, then decided it's too impractical to put a lot of resources into. I need to be able to field a good team against each type, not field a good team of each type.

But looking at my pokestorage, I have maxed or high level teams of 6 attackers for the following types: Fighting, Ground, Ghost, Electric, Dragon, Rock, Fire, Ice, Dark, Water, Grass, Psychic, Poison.
My Fairy team can solo Machamp but isn't all Faeries, they all just have Fairy charge moves. That leaves me missing a full team of Bug, Steel, Flying (could make with Hu Dragonites if I felt like it) and Normal (used to have before I trashed my Ursaring squad).

Dude, this is some solid work! I really like your teams. I do this as well except I invest far less resources in it. I just do with whatever I could catch/evolve and use this objective to decide what to transfer or not. I make sure I have at least 2-4 strong mons for each useful type, then I go as far as 8-9 pokemon per type for the most useful ones, but they are seldomly used so these 8th or 9th slots are taken by the likes of Sudowoodo for the rock team :) I only made sure they had double rock moves. As an example, my flying team stands out as being not very rich but I was surprised by the good performance of my double flying Pidgeot and Noctowl in Breloom raids! It was very refreshing to use pokemon otherwise never used.

A few suggestions :
* Switch out Slaking and maybe Blissey in your normal team. Wigglytuff would be better if you're short of Snorlaxes and Ursarings.
* For your electric team, I guess you will able to add another Jolteon soon, but you could also think about Wild Charge Arcanine. No Ampharos?
* A poison team is easy to build. A bunch of Sludge Bomb Gengars, double poison Victreebels, possibly some Roselias for the future and you're set.
* You could probably assemble a Fairy team with Wigglytuffs, Clefables, Donphans and Ursarings, unless of course you're blessed with Gardevoirs.
* Bug? Meh, my bug team is terrible, going down to a 1100CP Butterfree, so it's more for fun than for battle... Can't help here, this one is a tough one when you don't have Scyther/Scizor or Pinsir.

Nice work!
Some of those rare teams, like bug and steel, are really fun to use against their target raid bosses.

I love this project, dedicated more than a year to get this far. Sorted by type, all at level 40.

Not intentionally, it just happens over time. But I do have a team or two of pretty much the same types as you.

I want to do this but with 6 unique of each type with 90+ IVs, I know it won't be the strongest battle-wise doing it that way, but more of a challenge for my own amusement