Im new

A lot of the better pokemon are legacy sets, meaning unable to get those movesets these days (the big ones being meteor mash metagross, shadow ball mewtwo, sky attack moltres)

Currently available 'big five' (nonlegendaries) as I see it for raids and gyms(best, most sidely useful pokemon on offense, mostly gym related as I tend to focus the legendary raids more than the lower tiers):
Machamp for fighting type (tier 4 raids mostly tend to be weak to fighting outside of events, namely tyranitar) gyms tend to be a lot more diverse in what they are stacked with, but with dynamic punch and rockslide it can deal with most every common defender

Dragonite for dragon type offense and good on defense (rayqyaza is better offense wise, but its also a legendary, but dragonite-> via dratini is also very rare in the wild, but can be gotten via catch a dragon research reward dratini)

Mamoswine is the best ice type attacker and also a great ground type that hits defenders like metagross, melmetal and the flying dragons

Gyarados is currently best nonlegendary, non legacy water attacker with hydropump, second move of either outrage or crunch are also very good

Tyranitar with bite/crunch, hits a lot of legendaries across generations and 3 others in the current generation, good for attacking gyms are dark is faily unresisted by defenders

Notable ones I left out, espeon and mewtwo are good against machamp raids for getting machamp, find them less useful outside of this function.

Legendaries: rayquaza (massive neutral dps and best dragon attacker) Sky attack moltres (legacy move, but also best fire type attacker and flying attacker with both overheat and sky attack) and kyogre (best water type) left out because the rarecandy cost they need, as well as very costly to trade, bot in stardust and what others ask to trade for to get them if you dont have them.

Mewtwo's a bit situational, it has a lot of moves that are good damage, but its a very heavy TM rarecandy and stardust investment, as well as, from a DPS standpoint, less than other pokemon of those types (aside from psychic, which use of was stated prior)

Legacy move pokemon i'd see if people in your area have to spare are meteor mash metagross (best generalist), smack down tyranitar (also great gym attacker and in my oppinion best rock attacker), Lick gengar (very fast ghost attacker, but it is frail against ghost and psychic types), sky attack moltres (great flying attacker, with second move best/one of the best fire type attackers).
Shadow ball mewtwo, while it is good, is somethign I have found msot unwilling to trade, and theres a legendary in generation 4 (the current gen released/being released) that can be competitive with its damage output, or outright better in some scenarios, darkrai, also had shadow ball and is significantly tankier agaisnt ghost and psychic types (due to resistances)

Though thats just my own opinion, based on what ive personally found most useful, and for darkrai what ive seen from projections of damage output and match ups

I always tell new players, "Go to Gamepress. Any question you could possibly have is answered there. Often times in more detail than you need or want."

To veterans Pokemon Go is a simple game. It is for those of us that started in 2016 and have played all along. However, as a new player, the sheer volume of information and rules can be overwhelming. And a great deal of"what's good/what's bad" is highly subjective. However, for a good idea of what's good, peruse the top tier lists on this site.

There's simply no short cuts. If you want to know as much information as possible you simply have to do the work. That includes reading through this site.

I'll also say that, at least in my area, the veteran players go out of their way to hep new players. We usually spot them at a Gym for a raid. We introduce them to the Discord groups for the area (that's how we operate anyway) and get them plugged in. Players around here are very helpful and friendly. You'll get conflicting advice and opinions, but that's more a sign of how people play than it is on the game itself.

Jump in. Do the work. Find the local groups in your area and plug yourself in. That's truly the best way to learn. And most of the better parts of the game center around community interaction. You can play a lot of the game without ever needing anyone else. But the game is vastly easier both to play and learn with seasoned players.

This site may have all the answers, but unless you like reading volumes of information (I do) then other players is your best bet.

Answering you questions in this format in any sense would be near impossible to do completely.

in fact - if I remember right there's a good (albeit slightly outdated) article for new players on this site.

Welcome!
You have come to the right place.

Any specific questions you have, just need to be asked in here. The will be answered by a whole world of new PoGo friends.

I would suggest keeping an eye on this Q&A, as often people will ask and answer question we haven't even thought of yet.
Sometimes this is where I learn the most.

Happy hunting

https://pokemongo.gamepress.gg/attackers-tier-list

The most crucial non-legacy, non-legendary attackers are Machamp (with Counter + Dynamic Punch) and Tyranitar (with Bite + Crunch). Both are easy to acquire through raids.

Great budget attackers (until you find better alternatives):
1. Flareon with Fire Spin + Overheat
2. Espeon with Confusion + Future Sight
3. Gyarados with Waterfall + Hydro Pump
4. Exeggutor with Bullet Seed + Solar Beam
5. Jolteon with Thunder Shock + Thunderbolt

Highly useful non-legacy, non-legendary Pokemon that will take more effort to acquire:
1. Blissey with Zen Headbutt + Dazzling Gleam (gym defence)
2. Mamoswine with Powder Snow + Avalanche
3. Dragonite with Dragon Tail + Outrage
4. Rhyperior with Mud Slap + Earthquake
5. Electivire with Thunder Shock + Wild Charge
Special mention to Rampardos with Smack Down + Rock Slide which even many hardcore players do not have because it was only released recently.

If you have the chance to trade for a legacy Pokemon, the number one choice should be Metagross with Bullet Punch + Meteor Mash. Although Gengar with Lick or Shadow Claw + Shadow Ball is also great, inexperienced players may not know how to get the most out of them.

Accumulate stardust, TMs and Rare Candy until you know how to use them well.