Ahoy!,
I noticed that many people need help with PvP while thinking their gear or playstyle is not good enough. But in fact, many of those have the problem only with their crew. Therefore, I wished to help out with this problem. But a note before you go any further: this is only for people who can reset their companions, if you're a crown player and can't afford it, then that's an unfortunate fact for you.
For general class tips, ALWAYS, with no exceptions for any units who can get them, focus on Relentless/Burst fire/Mojo echo for fairly obvious reasons. Bladestorm is the second in the preference order, but you have to train on how to properly place the unit if you want it to be more likely to take down a specific unit in an attack chain/ combo. You may be thinking: what about Doubletap and Mojo rising? Well, those are obviously not as good as BS. Doubletap can sometimes be very good, and sometimes very bad depending on the unit's other epics. It can sometimes ruin Burst combos by moving hits to another unit that you don't want to be hit at that time, Nausica for example due to her dangerous True grit combo creating epic, or another unit with Quick draw or heavy protection. As for Mojo rising, it is just as rare as a pink monkey-faced chicken between normal ones. As for the other well known PvP epics, Second chance, Vengeance strike and other talents are a matter of preference, but I would NEVER want Cheap shot/ Parting shot. Now, let's start the class tips:
1.) Buccaneer : For buccaneer pirates' crew, the most common companion that is considered a MUST USE is too easy to guess: Peter Quint. He starts out with the most helpful talent, and the recommendation for ALL for companions who can get it: relentless. His most common build is relentless 3 and bladestorm. Although, you can give him relentless 2, bladestorm and second chance or relentless 2 and BS 2. Though the best build that I would recommend is the first one mentioned. After his last promotion, he gets a Super strike power and a Brutal charge. Relentless 3 can trigger like crazy, and since he gets A LOT of criticals, BS is almost guaranteed to trigger each turn you send him after a unit. The best more is to target musketeers or witches, either pirates or companions. Due to their low strength and dodge, he is likely to take a witch/musket unit down in a turn if you place him right where BS can't spoil his relentless chains on the specific unit. Other famous buccaneer-used companions are Baar, Zang Cha, Temujin, Goronado, Barnabus, Hawkules and Atohr. But remember: relentless should be in all except Barn, as he can't get it, so I would go with BS 2 and Vengeance strike. And a reason for why I would always use a full buccaneer team is very simple, the buffs. And I said Peter is a must for another reason, which is his Whale's might card. As for the talents for buccaneer companions, Strong 4, Accurate 4, Rough 4 and Tough 4 is the best build.
Till the next time with other classes!

Ahoy!
I'm back, finally! Let's now delve into the main subject. Enjoy!
When we last left, we were done with & . I would like to add, you don't have to use the same companions I've listed, just use the ones with best powers and epics. Now, we should discuss two more classes:
3.) Privateer : Privateer companions are pretty much swashbuckler or buccaneer companions but with slightly different stats and use will. Many people will find it obvious that I'll say that The Marchioness is the best in your team. She has Dispel Magic and the will buffs, guaranteed critical strikes and can get relentless, what more would you want? I can't say that there is any Presidio companion better than Lucky Jack Russel. He boosts will, starts with Bladestorm, and can train Relentless 2 and BS 2 as well. Catbeard is really good due to the will usage and good number of epics, but his damage isn't nearly as sweet as the other two. Nevertheless, I still recommend using him. Other companions are really really effective, but I would like to get gear with juju's to help them out. Give Egg Shen Relentless 2 and BS or Second chance, and cast a juju to see him go ape! Top companions: Egg Shen, El Toro, All the starter companion crown shop variants (excluding Zang Cha, you already have a goose!) , Goronado, Marchioness, Milo Graytail and the loooooong list of companions.
I'll resume on another post, I've ran out of space here.