So me and my friend have been playing Borderlands 2 for a while, we’re on our 3rd play through on UVHM, but on our last play through we played through the entire game, side missions and DLC, but the only missions we couldn’t complete were the Raid boss ones.
I see on youtube all these videos of people doing Raid Bosses solo eeasy pz with their high tier gear and such, but it’s always either solo or in group of 4. I was wondering is there a reason there isn’t a reason why people do it in duos ? is there a weird HP scaling on raid bosses in duo ?
and also not being able to kill the raid bosses at all never seem to be able to stack up any of the high tier gear people just shrek the raid bosses with. Any suggestions one what kind of gear would should atleast try to farm and which is the easiest raid boss to complete, aswell as build suggestions for duo? I’m playing Siren and my friend is playing Commando
Pretty much the only good thing me and my friend have currently is our legendary class modes since can get those from Torgue Vending Machines in one of the Torgue DLCs, and standard Bee Shields
Not in terms of health and damage that I’m aware of. I’ve done a few duo runs, also solo etc. The attraction of a four-player group is that generally you get more chances for better loot drops with more players. Certain raid bosses also have “per player” drops - that is, more chances at the really good stuff. Terramorphous is one example specifically.
Mostly, I think the four-player thing is just because it’s fun though!
The two of you should be able to wreck Pyro Pete together so you can farm seraph crystals etc. That will get you off to a good start so you can then go try someone else. Make sure you know the different moves and phases of the boss though - there’s tips and tricks for each and every one.
As previously stated, Pyro Pete is the easiest raid boss. I suggest that you get your friend playing the commando to get a fastball and DPUH and spec into grenade damage. The big boom blaster dropped by Pete is good for a grenade damage Axton too
Let us know which gear you have, and which level it is. And tell us which raid boss you wanna go after first, and we’ll see about getting you a good strategy that will get you going.
EDIT: Also… The level of your siren and commando would be helpful to know.
With a Siren and Commando you should be able to do Terra.
Theres a strategic rock the Siren can use for cover whilst using res on the Commando.
A bee and fire sandhawk , with fire bones if you can get them will do the trick.
What gear do you have ? Gear is important too. You can’t raid with most Purple rarity weapons and items or some terrible uniques.
I’d say you’re missing Moxxi weaponry, expecially if you’re new to the game.
Even with Maya you’ll need a Rubi at least; until you learn the fights, then you could try without.
For more complete help would you kindly:
1- use the above link to post your builds and
2- your gear of choice and their level
99.9% of the time I’ve played this game has been solo but the more players the more health raid bosses have as well IIRC. The more specific answers you give means better solutions you can be offered 
…
well our gear now is a bit scattered since we’re about 1/4 into UVHM now, we were trying to do some of the bosses at the end of TVHM, main one we did try was Hyperius since it seemed simple enough in videos that you just balance his shield off 1 robot and himself, problem was that by the time that last robot died Hyperius still had 3/4 HP, an d also cause we really wanted the Norfleet
this is what our builds are currently, though as I said we’re doing a play through of the game so it’s not a boss specific build
Commando level 55
Siren level 57
Pretty much only piece of gear with have set in stone is our Legendary Class mods. We have Bee shields but sicne we’re doing a new play through we’re gonna need a new one at the end of the play through.
though my playstyle on Siren I been running is generally an explosive Pistol, Fire SMG if I can get a good one as so some kind of rocket for self revive and I’ve been using Moxxis Kitten assault rifle
My friend on commando generally has a rocket for revive, assault rifle and a sniper
as for relics and such we don’t really have anything fancy at all since we can’t get any from bosses so we’re just using loot and XP relics and grenades keep upgrading them as we level nothing in particular. Though I did get a Fast Ball grenade on our last play through, it’s fun they’re still good on the next play through so far too.
(I do know in time though for myself on Siren I do want to get the Sandhawk smg, so I’m trying to hold on until we finish the game on UMVH mode till we do Captain Scarlett DLC so I can get a high level Sandhawk)
Right now during our play through we decided to jump into Sir Hammerlocks Big Game Hunt and actually been farming some of the Omnd-Omnd-Ohk’s powers ups as they’ve dropped a few Seraph weapons so far and we’re planning on trying Dexiduous
we tried doing Terra a the end of TVM using that rock glitch but it didn’t work and killed us anyway no problem so we gave up on him
Yeah , its not a foolproof method to be honest. It helps to have really good gear as well.
One thing with the youtube videos that I came to realise was that you only see the good runs.
Often there could be loads of failed attempts we dont get to see.
For the Commando:
http://bl2skills.com/commando.html#55055104015000000000005050144000
Laser Sight is quite possibly Axton’s worse skill and should never be used IMO. Also, Axton is all about his shield skills and he has 3 of the best shield skills in the game in his Survival tree- they should be used. Crisis Management is a skill for builds that might want to use a Rough Rider as a shield but with his shield skills it’s better to try to keep his shields up and recharging faster. Grit or Metal Storm should be the next skill to focus on for both survival and doing damage.
For the Siren:
http://bl2skills.com/siren.html#555101000005040000004550510501
Helios is a good skill but if you’re in FFL the damage from Immolate could bring you back. Chain Reaction and Kinetic Reflection are also both great Maya skills (not so much vs. Terra but still…) as is Wreck- look for a Mirrored or Blurred Trickster com to make use of KR/CR and really make it tough on your enemies to survive. W/o Moxxie weapons for healing Sweet Release is needed more than Mind’s Eye- definitely pick up Res though- the Commando player will love it 
You mention legendary coms but which ones? Standard would be L. Soldier for Axton and L. Siren for Maya so if you have those stick with them for now but be aware that some of the blue and purple class mods might be better suited to your builds and weapons. Speaking of which, anything Terra drops in TVHM will be level 50 at max so unless you’re using him for training purposes I’d forget about him for now. If you want to farm on level gear try the Marcus Saves Mercenary Day dlc, aka the Loot train- 30+ pieces of gear that is always on level and with a chance to spawn legendary gear (best I ever had at once was 2 legendary coms and a legendary shield). Good luck!
EDIT: Ninja’d by @Carlton_Slayer but I’m too lazy to re-write my post. Use both answers to your advantage!
Right! Let’s start with your builds. I’m a Siren veteran myself, but I can still give you a few pointers on Axton too. 
For almost any siren build, Ward is very important. I’d suggest you max it out. Especially since you have a Legendary Siren at hand. It will give you 10/5 in Ward, which is extremely helpful against all raids. Sub Sequence is one of those skills that you either love or hate. I’d never use it, unless I used a Thoughtlock build. Which I never do, so I never use SS. In any case… It’s more or less useless against raids, since there are only a couple of them that have minions that can be phaselocked. This affects other skills too, but we’ll get to that later. Quicken is also less important for the same reasons. A Bone of the Ancients, along with your COM, will give you plenty of cooldown as it is.
If there are no minions to phaselock, then there are several skills that become useless. However… You’ll still have the best slagging tool in the game when you’re speced into Ruin. If there are minions to phaselock, then I’d go something like this. While both Accelerate and Mind’s Eye look really good at first, they don’t add that much in reality. One point in each, to reap the benefits from your COM, is enough.
If there are no minions that can be phaselocked, then I’d go like this. Sustenance and Life tap are great skills against raids, so consider them when you have more points to spend. You’ll have to send points in skills that are more or less useless to get there, but it’s often worth it.
One skill in the Cataclysm tree that I always recommend is Immolate. It may not look that attractive, but it adds tons of damage when you really need it. You’ll see also that I put a few points in Inertia. It’s a really good skill, especially if you’re using a Bee. The Bee doesn’t offer much protection, and has a long delay, and that’s when Inertia comes in handy.
For Axton, it’s equally important to keep the Bee at full. I made a few changes to your build here. Increased health is generally not that important in UVHM, so I skipped the points in Healthy. While Resourceful is a good skill, I still feel that you’ll need the points in other places for now. Longbow is great for deploying your turret away from you, and thus draqing aggro away from you.
What’s important to know is that a few of the raids, including Terra and Hyperius, wash off the slag almost immediately. Therefore it’s a good idea to use a Slag Bouncing Betty / Bouncing Bonnie / Crossfire to slag them repeatedly. This will make life a lot easier for you. Moxxi weapons is also very good to use. Grog Nozzle or Rubi is most players first choice, but the Kitten is also really nice. Only problem is that you have to be fairly close to land the hits properly, and that rhymes badly with the Bee. Consider getting a couple of Good Touches from Moxxi instead. Very good against both these raids.
as @Carlton_Slayer and @Ronnie_Rayburn say, Carlton_Slayer commando build is virtually how I run my commando and works very well.
as for his Siren build if the Commando has Slag on his turrets, my thinking is the one point in ruin might possibly be able to be used in “RES” instead, a little more like Ronnie_Rayburn builds for the Siren
Most relics come from world drops, actually. There are a few missions that offer relics as rewards. The only boss drops that come to mind are Blood of Terramorphous, which is super rare, and the Sheriff’s Badge. The Sheriff’s Badge is well worth farming for, but only if you’re running pistol builds.
LLM’s (Legendary Loot Midgets) have the ancient E-tech relics in their loot pool, which they drop very often. The most common method to farm for one is by keeping the mission “Doctor’s orders” open. It becomes available by the time you’re getting ready to visit the Wildlife Exploitation park. Accept the mission, but DON’T PICK UP ANY OF THE ECHO RECORDERS!!! NOT EVEN ONE! Farm the midgets in the four boxes for relics and other shiny objects such as legendaries and pearlescents.
When you’re done with the LLM’s in the room, you run back to the entrance to the Natural Selection Annex. Enter it, and then exit it so you get back in WEP. Then you save & quit. When you re-log, you’ll be outside the entrance to the Annex. This will save you a trip through one of the most dreaded areas in the game. You need to do this every time you wanna keep farming, otherwise you’ll spawn at the WEP entrance instead.
Sounds like someone has too much eridium on their hands and desperately seek a way to get rid of some. 
While build matters of course, it’s important to consider the main danger of raid bosses, which is their unblockable attacks. Everything else is just timing and patterns, but you have to deal with those unblockable attacks. For Pete, it’s his elemental novas, for Hyperious, the double novas, for Gee, the acid pools, for Vorac, the double novas plus everything else. For Dexi, the Dragons, and Craw, stay out of the way and move as they don’t have any unblockable attacks. That doesn’t mean the latter three are easy, particularly the Dragons because they have so many attacks.
Therefore, you want a Moxxi weapon to heal you between Novas, mainly the grog which also slags. For Hyperious, the Hoplite shield, available from Pete, is great for Axton because you can take a Nova and stay above healthgate below OP levels. You can then grog up to full health before the next round. For Maya, you can use the grog or an emergency phaselock with a grog in between novas. You want to save your phaselock of course for Res, but you can use it if need be. It’s just patience and repitition, which is one reason I find the Raid bosses in BL2 fairly uninteresting, because the difficulty comes from dealing with the unblockable attacks and the timely use of the Grog.
Edit: For Terra, the rock glitch is not absolute, you have to move for the rock throwing tentacles and the few times Terra comes up on your side of the rock. Maya can use the grog and phaselock to stay above healthgate in those situations, but Axton needs to move to the other side of the rock.
terra isnt that hard if you know how to deal with him. use the rock for cover and kill tentacles basically
the rock throwing tentacles are especially bad, kill them asap and dont forget to dodge their rocks
use a fire sandhawk and the bee and it shouldnt take too long. you need a non fire weapon for his fire tentacles and fire phase, the dpuh should do it for those parts
a cat class mod is better than the legendary siren for maya for this fight since nothing can be phase locked
build I have now is kinda just a destroyer build for my Siren I’m using just to clear through the game, it’s not my boss build, just looking where I move points around to pick up better things for bosses