Borderlands 2

So this is the most grindy achievement of bl2, its easiest with the character you played most with and you get it by unlocking all lvl 1 challenges.

Some of the hardest ones are:

Blue Sparks (Vehicle): There is a big chance you haven't made any progress in this section, understandable, I had the same after doing all my playthroughs. To get these you need to power slide over enemies. To do this you use the handbrake and turn the vehicle towards enemies. Here is a bit more explained how to do it: tutorial on powersliding by SheDevil

JEEEEENKINSSSSSS!!! (misc): Kill Jimmy F****** Jenkins, there are a few methods online and having tested quite a few I can say with confidence that having the Mission octers Orders active, then going to wildlife resort until you reach the room with the 4 small boxes WITHOUT taking the mission objective, is probably the fastest. To speed up the grind a bit you can go in the wildlife Annex (the arena) if you have the dlc for faster Save and Quit reloading. HappyThumbsGaming detailing the method

#Hidden challenges:

Catch-A-Rocket (hidden): To unlock this one you have to complete the level 5 challenge of Splish Splash, it is pretty grindy. My best advice would be to go to an area with a lot of enemies and fire away with a high magazine size rocket launcher (preferably on normal difficulty for that sweet one shot). Once you complete the lvl 5 challenge there is a big chance that the first few levels will unlock automatically since it already counts your progress from before unlocking it.

Shotgun Sniper (hidden): Analogue but now you need lvl 5 Open Wide, this one is a bit more tedious as process will be slower if you played a character where you didn't use shotguns that much.

There are of course plenty more challenges but these were the ones giving me the most trouble (F*!,lk, Jenkins...)

If this guide helped you or you are having trouble with another challenge feel free to send me a message and I will try to adapt this as soon as I get the time!

IMPORTANT: I didn't mention it above but you do NOT need all challenges listed, with non level specific they mean areas, all challenges regarding finding all the vault symbols are not required aswell as the DLC challenges these are not needed aswell.

There are already lots of great guides for strategies during the boss fight itself, but here's another bit of info that will make this extremely easy.

Complete the "Fight For Sanctuary" DLC with True Vault Hunter mode and receive the Toothpick (Assault Rifle) and Mouthwash (Relic) effervescent items as part of the story quests. Under TVHM, these will match your current level.
Then return to Normal mode and complete the DLC again in order to start the Haderax mission. In Normal Mode, Haderax will max out at level 40, making it extremely easy to kill with your overpowered effervescent items.

This achievement requires you to defeat the Raid Boss "Terramorphous the Invincible"

This achievement can only be completed after the main story is finished. It is highly recommended to finish TVHM (True Vault Hunter Mode) first, as that will set you to around the same level as the raid boss (Level 50).

Once you have beaten the main story, go to Tannis in Sanctuary, she will offer you a side quest called "You. Will. Die. (Seriously)"

Accept the Quest and go to Thousand Cuts.

Once at Thousand Cuts, go to Terramorphous's lair

Once at the lair, you must put down 8 Eridium to summon Terramorphouse

After Placing the Eridium, the door will open and you can go to Terramorphous Peak.

Go through Terramorphous Peak until you reach the Vending Machine. STOCK UP ON AMMO OR ANY OTHER MATERIALS, YOU WILL NEED IT.

After you have stocked up, Drop down the hole and run over to the podium. Once you press the button, you will start the battle.

Tips for Beating Terramorphous

Terramorphous hits hard but slowly, so try to dodge his attacks to prevent massive damage. He is also very beefy, so I reccomended bringing a slag gun to Slag him and wittle him down faster. The Conference Call or Unkempt Harold are very good weapons to bring to this fight. (My loadout was a Crammed Unkempt Harold (LVL 34), Akurate Slagga (LVL 41), Gunstock Maggie (LVL 41), and a Potential Conference Call (LVL 50). As well as a LVL 49 Bee Shield for Bonus Amp Damage) (My Inventory)

Terramorphus has some Tentacles that will sometimes pop out of the ground during the fight. I personally saved these until I was in Fight For Your Life, because killing these Tentacles will give you Second Wind. The Tenctacles also drop a Lot of Ammo if you ever run out during the fight. They never really bothered me during the fight as long as you dodged their attacks.

Once you have beaten Terramorphus, the achievement will be unlocked.

P.S.: This side quest is required for the "Do It All" Achievement.

This achievement requires you to open a chest in Fyrestone (Yes the same area from the beginning of Borderlands 1)

Near the end of the Story, during the mission "Data Mining", once you go to the location "Arid Nexus - Badlands" (You can fast travel here if you already beat the main story), go through the town of Fyrestone until you see this red house

Get on top of this house and there will a chest on top.

Open this chest and get the achievement

Visit all the "greyed" out areas of all the different locations in the Pirate's booty DLC.

These areas include: Hayter's Folly, Oasis, Wurmwater, The Leviathan's Lair, The Rustyards, Magnys Lighthouse and Washburn Refinery.

The most common one that people have not gotten is at Magnys Lighthouse. At the far end of the map there is a "Secret Stash" wich is a small room inside a building. Go there and you will get a pop up notifying you that you have found a new place on the map.

If you have looked everywhere and still haven't gotten the achievement i would recommend this site: https://borderlands.wikia.com/wiki/Category:Captain_Scarlett_and_Her_Pirate%27s_Booty_locations

It gves you a lot of usefull information about the area in hand and can help you towards getting the achievement!

Hope this guide was helpfull and that you are one step closer to completing Borderlands 2!