Like in the 300s? I'm still only level 7 so pretty far off having a high CP pokemon.
If I'm to be completely honest here, and im not saying this biasedly,
Heres the benefits/cons I've noticed
Team Valor: They have the numbers to overwhelm others gyms. The more gyms you hold, the more pokecoins you receive every 21 hours, making it a LOT easier to purchase lucky eggs from the shop. (Do NOT waste your coins on anything else. They're a waste of money.) The only issue I've noticed with them is that they're kind of arrogant. Not all, but most that I've met.
Team Mystic: We're underrated, but we're close knit because we're not as diverse as Valor. We're still capable of holding gyms, BUT honestly only if you know a few friends that can toss higher level pokemon into the gym with you. We dont have the numbers, but we have power and (at least around here), we have the power to hold gyms, just not the numbers.
Team Instinct: Very underused/rated team. very low chance of holding gyms due to, again, lack of numbers, except its even more of a disadvantage based on numbers. I cant really get into positives since I really dont know much about how they are as there are not as many around here to gauge.
Overall: It comes down to what is more appealing to you. being only lv 7, I'd reroll for what team you actually want. A tip: If you already spent money on lucky eggs to level, save ALL your weedle/pidgey candy and depending how much candy you have, save about 10-15 of each. They cost 12 candy to evolve and with lucky egg activated, you get 1k per evolution. during that time the egg is running, evolve everything you can. I went one and a half levels doing this, and I went from halfway into 17 to 20 last night with 3 eggs.
With egg active:
Pokestops - 100xp plus double bonus for curveball or nice/great/excellent. Try to drive to an area with multiple close pokespots. The area I go (Screenshot above) has about 20+ in a 15 minute walk, that alone is 4k xp per egg. I have spent 11$ for the 25 eggs since this is a very easy way to level.
Catching pokemon - 200xp. Aim for ALL pokemon, but prioritize weedles and pidgeys especially, as 4 = an evolution, so 1800 xp for that.
Evolution - as mentioned, 1k per evolution. save up all your candy (Even others besides weedle/pidgey as all evolutions are extra XP!)
Also: DO NOT WASTE YOUR TIME EVOLVING/LEVELING UP YOUR POKEMON UNTIL YOU'RE ROUGHLY LV 15!!! You want to save as much stardust as you can because leveling up starts to gets insane once you get into the thousands. Im at 1500 and its costing me 3k dust and 3 candy. On top of that, the higher the level you are, the higher the pokemons starting CP you will find. I got a 505 oddish last night I evolved into a 9-something gloom. Once I evolve it into its next stage, Im probably looking around 1200 (RNGesus bless me) to start. Trust me, the more you wait, the better off you will become, so be patient. There are other tips on how to level/train, but these are your basic strats to help you become the very best, like noone ever was...
Edit: I had a bunch written when I started to edit, but got erased somehow and cant undo. the short version of what I said was dont waste time using modules unless you see one active and have an incense. From personal experence, you're get between 7-9 on average, and with incense, maybe an extra 5 or so.. all low CP, so while it may be good stardust/evolution fodder, its not worthwhile in the long run in my opinion.