you should figure out what move set you want for each pokemon. Most pokemons are either good attacker as counter to a specific defender or raid boss, or good defenders. In each case, there is usually 1 optimal move set. Figure out what it is for each pokemon type and only keep those with the right moves and high enough CP or IV.
Then, it's hard to justify keeping many pokemons of the same type. Except for raid teams. The only one I really keep a lot of is Machamp because it's so usefull is gyms but it's fragile.
For example, I try to not keep more than 6 of each eevolution, each with good moves and IVs, and that's already a lot.
In the end, I probably use the same 20 pokemons 90% of the time (attack and defense) and I could get rid of all the others.
Cleaning Pokémon storage.
Now with the event coming to a close I can't think of a better time to start transferring Pokémon but I've never been any good at. How do some of you guys keep your storage nice and clean?
Answers
I have 6 or around 6 of these, all with the right moves (often times TMed) and good IVs, so yes I keep them.
I do keep multiple of machamp, golem, rhydon, gyarados, exeggutor, lapras ... with good moves (sometimes more than 1 move set) and decent CP because during some long battles it's nice to be able to keep fighting without spending time healing. But it's good to set a upper limit, like a multiple of 3 so it makes rows on your screen :-)
I keep a lot for sentimental reasons, but really, 0 or 1 of each for almost all the other is enough
I keep one of each Pokémon with the best IVs I can find, so any Pokémon I catch, whether it be a Pidgey or Dunsparce, I appraise their IVs. If it's not to my satisfaction, then they are transferred on the spot. If they have good enough IVs, then I keep them until I find one with better IVs (or perfect). Once I obtain a perfect IV Pokémon, I transfer everything else of the same species, even if it's 98% IV.
This method keeps my Pokémon storage less than 200 Pokémon, even though my current max is 400, and filters out any unwanted Pokémon. I will definitely be doing this when Gen 3 hits, but I'll probably try to upgrade my storage, just to be safe.
Yup, I only keep one of each Pokémon, including the ones you've listed. The only Pokémon that might break that rule is Dragonite, since the one I currently have is 95% IV and has Dragon Breath, a legacy quick move. I definitely do not intend to transfer this Dragonite, but I'm not sure what I would do if I manage to come across a perfect Dratini, to be honest. :/
Honestly this comes down to your personality and desired gaming experience.
If all you care about are gyms, then attackers, and perhaps defenders take priority.
If you're a collector, then perhaps having a high IV of each is desirable; maybe more space for shinys, event pikachu's etc.
If you're a "What-If" gamer, then transferring pokemon that could be good if given a buff or tradeable might jangle your nerves.
If you like to solo Raid bosses or see how few trainers it takes to take out a Suicune then Teams will be your focus.
Personally I keep high IV Pokemon (that includes my 2x 98% IV Weezing) and then focus on Meta Relevant mons. Fact is Niantic will change the rules and with each new Gen or roll-out, needs will change. With infinite possibilities and finite space I suggest you keep the mons you like the best, use the most or find value in.
Remember to enjoy the game - it's shouldn't be exclusively about raw stats and optimization. If adding santa hat pikachus in every gym during the holidays makes you smile... keep the little yellow imps.
