After many hours as various professions in various group sizes in WvW, I can say one thing for certain: PvP combat in GW2 is a beast all its own. It doesn't really fit into any MMO "mold." However, I've found many conceptual similarities between Small Gang combat in Eve Online (5-10 players per gang) and small group skirmishes in GW2 WvW. To clear up terminology for the unfamiliar:

Tackle: Players dedicated to the role of preventing a target's escape and generally being "heroes" (dying in a ball of glorious fire).
DD: Main Damage Dealers. With very few exceptions, everyone in a small gang should be trying to do damage, but some should be focused on it.
RR: Remote Repair. They're rarely seen in smaller groups, but they can be invaluable for extending the life of the gang by "healing" other players during (and after) an engagement.
EWar: Electronic Warfare. These players focus on disrupting the combat abilities of the target(s) by reducing their effective range, stopping their attack, or otherwise preventing/hindering them from performing what they want to do.

Before you read further, please note 2 things:
Every Profession in GW2 is capable of doing each of the above concepts with a reasonable level of efficacy.
The examples given below are just that: examples. They are not hard and fast rules, they have just worked for me and my squad when we roam as a small group.

Tacklers
Sword/Dagger Rangers + Alpine Wolf: They have a 2s cripple on a 1.5s auto attack rotation, 2 attacks of which are on short leaps, which is great for chasing targets you're already close to. Crippling Talon is a ranged cripple, good for catching up to a target or getting them to use their escape while you close the distance to pin them with your sword auto. Alpine Wolf has a chill on F2 as well as a cripple and knockdown in its rotation.

Sword/Dagger Thieves: Similar to the ranger, they have a cripple on their 3rd auto strike. However, due to the strike timing the cripples do not overlap like they do with the Ranger. The spammable Dancing Dagger skill is great for maintaining multiple cripples across a group of targets. Scorpion Wire is excellent for pulling in stragglers, and Caltrops (the utility) maintains a superb cripple.

Dagger/Scepter/Focus Necros: 3s Immobilize on Dagger 3 (Dark Pact) and a 5s Chill on Focus 5 (Spinal Shivers) is a great combo for tricking someone into blowing their escape. Grasping Dead (Scepter 2) is a 5s Cripple on a 10s CD. Spectral Grasp has a longer range than Scorpion Wire with the same cooldown, and applies a 4s chill when your target gets to you.

Damage Dealers
Warriors: Any weapons will really do here, depending on your Traits and playstyle. Even the Mace auto attack hits like a truck.

Dagger/Dagger, Pistol/Pistol Thieves: Daggers for obvious high damage/single target reasons, but Pistols are often overlooked as superb single target ranged damage, especially when combined with haste and traits.

Staff, Dagger/Dagger Elementalists: Staff can drop great AoE damage on a group of enemies if your squad has good control in place. Dagger/Dagger brings mobility and high single target damage to the table as well.

Shortbow Ranger + Eagle: This guy is a machine gun, and the single target spike+bleeds from the eagle is something to be reckoned with.

Remote Repair
Mace/Shield, Staff Guardians: The AoE heal from the Mace is an oft-overlooked but very effective heal, while the Shield abilities serve as excellent protection in a pinch. Staff also brings great heals to the table.

Water Elementalist: Ele water spells, pretty much 'nuff said.

Elixir Gun + Medkit Engineer: 10s AoE pulse heal on a 20s CD with the Elixir Gun, plus bandages and condition removal with the Medkit.

Shout Warrior: The Shouts Heal trait combined with the -20% Shout CD trait makes for some mighty powerful shouts. You're adding boons to your allies as well as healing them with each one.

Ewar
Scepter/Torch Mesmer (really, any Mesmer): Confusion and Blindness causes enemies to miss and hurt themselves. Having any Mesmer with you will work wonders because they're generally confusing as hell to fight except for the most experienced PvPers.

Sword/Pistol Thief: AoE blind field that uses initiative alongside other utility smoke fields (blinding powder, smoke screen) can totally negate the damage output of a an enemy group for a few seconds. Shadowstep on the sword makes it easy to get in and out without much fuss.

Turret Engineer: Turrets don't do much damage, but they enable your squad to control or disrupt another group because turrets perceived threat is much greater than their actual threat.

Condition/Epidemic Necro: A well timed Epidemic can potentially immobilize/cripple/poison/bleed/blind/weaken/vulnerable an entire group of foes. This is a day-ruiner on a 15s CD. You can practically run with it on Auto Attack during a fight.

What you can do with these examples

The following assumes you have some kind of VOIP available to you (Skype/TS/Vent/Mumble).

1. Once everyone has settled into an overall role and someone has accepted (or taken) the role of squad commander, set out into the field and see how you fare.
2. Calling targets and focusing people down is the idea, so use target calling as much as possible.
3. Focus on your role first and then dealing damage/surviving second (unless damage is your role).

You should be able to do this with a group as small as 4 or 5. Remember that smaller groups need damage first, then tackle, then everything else.

TL;DR: Some classes really excel at specific things in a small- to medium-size battle in WvW. This posts aims to start discussion about selecting a tactical role in a small group, and then arming/traiting yourself for that role, all within the context of similar tactical roles in Eve Online.

Disclaimer: Since combat in Eve Online scales much more vertically than it does in WvW, it's best to take everything in this post at its simplest conceptual level.

Originally posted on gw2 reddit by BrainKatana

oooo ya all kinds of tournys require us to build our own party of 5.

so those tournys that require tourny tickets ... better loot if we win the tourny? O_O