What do you think of my Prestige-only Team?

Hyper beams are pretty rough on prestiging, always take damage while charging which is a pretty big deal when you are at half the cp.

Tangela is a good grass option after the buff. They do fantastic for prestiging, I've got a few in the 1300 range and they are very handy.

You'll probably want multiple bugs, if you miss a single dodge the bugs get smashed immediately.

They look a decent selection. It depends what you're fighting against. I frequently use disposable pokes for prestiging - e.g. 8-900 Pidgeottos, evolved and unpowered up egg hatches where I have a surplus of candy - Kingler, Magneton, Venomoths, Golducks, Seakings etc. Hypnos or even high CP Drowsy tend to work well too.

Good Generalists:
Hypno, Ratticate, Wigglituff

Waters:
Golduck, Starmie, Seadra

Electrics:
Raichu, Magneton, Electabuzz,

Grasses:
Parasect, Tangela

Bugs:
Parasect, Scyther

Ice
Cloyster

Disposable:
Ratticate

In addition to these, you can of course use all other pkm that are usefull for attack, if CPs match.

I have many of them, from 1000 till 2000 HP. I do not build a real team actively, i just do not throw them away after lucky-egg-evolution.

Most guys in your team are usefull, i just don't like Victreebel because of sludge bomb not being grass.

I always focus on the lowest level guy in the gym, try to find a decent matchup, and then bail after defeating just that one defender. If my attacker is half the cp of the first defender, I can add 1000 cp after defeating that first defender. The key is that everyone on the team has to be at half the level of that first defender. If I have a good matchup and can dodge, my first matchup sometimes doesn't even die.

There are a lot of good resources on matchups, but i really like raticate with bite/hyper beam against snorlax for prestiging a gym. Bite is a very fast move and makes it easy to dodge anything but body slam.

These are my prestigers.
1) Grass Types are all Vine Whip + Solar Beam, except for one Tangela with Vine Whip + Power Whip. Two Parasects with Bug Bite + Solar Beam are fillers.
2) Bug Type, Bug Bite + X-Scissor Parasect.
3) Electric Types are all Thunder Shock + Thunder.
4) Ice Types are all Frost Breath + Blizzard, except for that Dewgong with Ice Shard + Blizzard.
5) Water Types are all Water Gun + Hydro Pump.
6) Others: Pound + HB Wigglytuff, Bite + HB Raticate, and WA + H Pidgeot. They're mostly for Snorlax, also fillers. Pidgeot simply always amazes me. It can accomplish anything!

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Before the CP update, I actually plan to acquire a high level Pound + Body Slam Jigglypuff. This move set is, in my option, even better than DB/DC of Dragonite. Also, Jigglypuff's high STM makes her actual performance much higher than her CP - exactly what you want for a prestiger.
But now that she got nerfed, it is just a remote dream...

With the starter event still going try and get an Ivysaur with Vine Whip/Solar Beam and do not evolve it. The first evolutions of the starters are just as good for prestiging as the final ones and good grass Pokemon are especially useful. I find prestiging much more difficult than beating an enemy gym. There are so many different situations.
Recently someone gave a very good explanation on the Silph Road:
https://www.reddit.com/r/TheSilphRoad/comments/5ln98o/clearly_i_dont_understand_prestiging_help_me_out/

Check out the reply of Tdshimo it should come up nearly at the top if you sort by best replies. Everything you should know about prestiging is in this post.

Out of your line-up the Wigglytuff is by far the best allround prestiger. Raichu is also fine if you need electric. Parasect with Bug Bite/Solar Beam would be a good addition. Also Tangela with Vine Whip/Solar Beam if you can find one.

Interesting is also this post about CP efficiency, this is the damage Pokemon deliver at the same CP. Some very surprising results there, like Wartortle being better than Blastoise at the same CP.
https://www.reddit.com/r/TheSilphRoad/comments/5l9jtr/wartortle_ivysaur_are_excellent_for_prestiging_cp/

Final remark: Anything I catch that has CP800 or over and that I do not want to keep I rename @ immediately. When filling the 6 slots to prestige a gym I first pick my real prestigers for the first 1 or 2 (or maybe 3 or 4) Pokemon in a gym and then fill the remaining slots with my @ selection (sort by name and they come to the top). If they faint I transfer the @ mons for a candy without reviving them. Depending on the strength of the gym and what is in the bottom you should be able to get 2000 to 3000 points per fight even if you miss a dodge once in a while like I do. The most difficult gyms are the ones with Snorlax and Lapras with good moves at the bottom I find.

If eevee is common near you, then stick to eevee evolutions.

I had more Eevees than I know what to do with, basically just started evolving them for XP during my lucky egg sessions. I tried to evolve them at various levels for prestiging.

In the 250cp-1400cp range, I have 12 Vaporeons (10 HP 2 AT), 14 Jolteons (8 Thunders, 6 Thunderbolts), and 14 Flareons.

If I evolve a "prestiging" range mon with either aqua pulse, discharge, or heat wave, I basically just use it once and then transfer it.

I don't even try and go out looking for eevees, they are literally the 3rd most common pokemon in my area. According to my pokedex ive caught

1,537 pidgeys
928 rats
667 eevees
491 spearows
430 weedles