Too many questions from a new player...

Holy crap...

First of all, since you are level 30 you can now get level 30 wild pokemon and level 35 weather boosted pokemon. Find some higher level (33-35) pokemon like machop and geodude that you can evolve but not have to spend stardust. Even if the IVs are not the best it wont matter that much they will be very helpful. Dosent have to be the best moves right now either. Example rock blast golem are good enough as is close combat machamp. Just dont spend stardust on them.

Keep powering up your Dragonite for sure. Power up that venusaur with frenzy plant too.

Only spend stardust on high iv pokemon and try not to bring one up from too low of a level.

Do not spend rare candy on non legendaries.

Power up your best moltres and at the end of May power up your best zapdos.

Try to do some raids at ex locations near you if possible. Starbucks and Sprint stores are known to give them out from time to time. That way you can get yourself a Mewtwo hopefully.

Do not use your limited resources topower up mew if you got one. Its cool but not that battle relevent and you have bigger needs.

The most crucial non-legendary attackers are:
1. Dragonite with Dragon Tail + Outrage. Yours is a gem!
2. Tyranitar with Bite + Crunch. Depending on your area, you may easily acquire them from raids. If not, Larvitar is an excellent buddy candidate.
3. Machamp with Counter + Dynamic Punch (Close Combat is strictly worse but usable except against high-level Blisseys). Evolve your 91% level 20 Machop and hope it gets DP. If it gets Heavy Slam, using one Charged TM guarantees an improvement.

How many Rare Candy do you have? Save them for Zapdos, as a 96% Charizard with an exclusive move may be better than Moltres (Flareon with Fire Spin + Overheat is also a great budget Fire-type attacker).

I'd recommend just studying the Raid Boss List and Counters guides on this very site. It's gonna be much more detailed about which Pokemon you should focus on and which movesets you should aim for.

For fire types, try to hang on to that Charmander for now. During Community Day (May 19th), if you can evolve it during the event window, you will have a very good Fire-type attacker on your hands. The Moltres is certainly worth maxing at some point, and I believe we're at the last week of Moltres so you don't need to worry about getting a better one. Flareon really isn't worth the effort since it's only level 10.

That Blissey is fine for Gym Defense. Don't worry too much about it since it alone should be fine for getting you gym coins depending on your area.

I would focus resources on Moltres and buddy that one Larvitar that you have. Gyarados is definitely worth powering up, and I would hang onto the Frenzy Plant Venusaur, but for a lot of your options (For example with Flareon, Exeggcutor, Espeon/Alakazam, and Rhydon), I would, as Lawman8839 suggested, look for Weather-Boosted high level Pokemon as opposed to using stardust on what you have. Save the Stardust for the rarer choices such as Gyarados and legendaries.

If you have tons of exeggutors powering them up is the best option as far as grass type is involved. Charizard and Venasaur are not worth it unless their evolutions are added which is not likely in the near future.

1) Generally, you shouldn't power past L31 without a specific reason. Power that Dnite a few more times and shift your focus.
2) Be very selective about what you power up from a low level (sub 20). FP Venusaur is worth it because you can't get another.
3) Don't use stardust on defenders. In the current meta, if someone wants to take a gym down, they will no matter what is in it.
4) Prepare for Tier 4 raids. Since you mentioned that you have a group of 3 or 4 regularly, tier 4 raids are doable with some preparation. To do that, raid Machamp until you and your group have 4-6 good ones. Walk Eevee for Espeon and raid Exeggcutor if you need to. Psychic and Solarbeam preform similarly against Machamp in neutral weather. Don't use any move called "Seed" unless you target is weak to grass.
5) Wait for ComDay on that Charmander.
6) Tier 3 solos take some patience. You have to go after each boss individually. By the time you are ready, the boss could rotate out, and you would have wasted you resources. Machamp and Gengar keep coming back, so focus on them first. You may stumble across (or have already) Pillowswine counters since he is the easiest tier 3.

Well that should keep you busy for a bit!

Doesn't sound like you are new, if you are level 30.

If you need to fill out your attacking teams, look for wild, boosted species (level 30-35 or 5000-8000 stardust cost to power up). Things like Abra, Machop, Eevee, Magikarp, Gastly or whatever is common around you. Even a Pokemon like Ursaring can fill in some gaps if you need it to. It's okay if they have mediocre ivs. For instance, if you build a team of Alakazam/Espeon at level 32-35 with ivs in the 60s it higher, add in your Dragonite, you should be able to solo machamp.

If you can find Eevees, evolve all them over 700cp. When I was in the level 30 range, Eeveelutions were my lifeline into gym battles. Eventually, I replaced most of them with things like Machamp, Dragonite, and Tyranitar, but my top Flareon, Jolteon, and Vaporeons won me A LOT of battles.

I wouldn't spend stardust on anything below level 20 and very few things below level 25. Your level Alakazam is awesome, but probably not worth the investment at the moment.

Other than that, the top comment on this thread is excellent advice! Good luck!

Check out this thread from a while back. Lots of good stuff in here.

https://pokemongo.gamepress.gg/q-a/if-you-were-pokemon-coach-what-would-you-advise-your-players

Based on what I see, I think you have been a little too focused on IV up to this point. You have some great high IV stuff that is not at all useful. For example, 96IV but L3 C/FS alakazam. What ever attack set your bad espeon has is undoubtedly more useful because it is probably much higher level?

Rare stuff like Beldum or bagon? Be more selective. Wait for 89+ or 96+ or whatever your threshold is but Common Pokémon like exeggcute—>exeggutor evolve even a L30 0IV or certainly a L35 50IV. They will be awesome compared to what you have. Upgrade after you get powerful commons....a team of high level Extrasensory/Psychic or E/solar beam exeggutor can solo Machamp without them all being 15 attack or 90+IV.

Note: I just finished maxing a 98IV rhydon that started as a L1 rhyhorn before TM existed. It was my only top tier Rhydon with the right moveset when the project began. So, I certainly understand where you are coming from. With TM and weather boost, I would not do this again. I have a 100 IV L1 growlithe that will probably be a L1 100IV Growlithe or arcanine forever.