Bonus parts - Successfully complete the indicated task to unlock the corresponding part:

07-Moonlight (laser blade), ASB-0710 (additional boosters shoulder piece): Defeat Orca Rank 5 Next Shinkai.
All purchasable parts: Successfully complete both the Collared and ORCA story mode.
EC-0307AB (triple back laser cannons): Successfully complete the "Attack on Carpals" mission in Chapter 3.
Salineos (split missiles) and 051ANNR (assault rifle): Successfully complete the "Defeat White Glint" mission at the end of Chapter 2.
White Glint Head, Core, Arms, Legs, and Head (top) Stabilizer: Successfully complete the "Defend Line Ark" mission at the end of Chapter 2 (White Glint does not have to survive).

ORCA story path - In Chapter 3, successfully complete both the "Defeat Red Rum And Stark" and "Destroy Megalis" mission to unlock the ORCA story path. The first ORCA mission is "Destroy Arteria Ulna".

AI - Compared to Armored Core 4, the Nexts are much quicker. The quick boost thruster consumption appears to have been reduced and this causes quite a few of the AI to move very quickly and very erratically. Tried and true methods that brought down Nexts in Armored Core 4 do not always work, such as the ever potent HLC02-Sirius. The developers have compensated for this by giving placers the back chain guns GAN-01-SS-GC obtained by following the Collarred story line. Combined with the INBLUE FCS, which has the highest lock speed, and rapid quick boost techniques to stay close, you can easily destroy almost any Next. Unfortunately this is not available until after the "Defeat White Glint" and "Defend Line Ark" missions, which are very difficult without these chain guns on your back. Very few Nexts utilize aerial combat techniques; mainly Fragile, White Glint, Ambient, Stasis, Old King, and Unsung. Also, laser blades can use lock on now, making it easy for Nexts to target you with their blades. Shinkai is the most dangerous and is found in the Defend Arteria Cranium (final mission for Collared) and can very quickly take you down to size using homing strikes from the 07-Moonlight.

Recommended equipment - FRS distribution

Capacity

Category 1 Load (allows heavier Nexts)
Category 2 Energy Output (more energy for flying and energy weapons)
Category 4 KP Output (greatly enhances Primal Armor)

Primal Armor

Category 2 Core (another great boost to Primal Armor)

Boost

Category 1 Main Thruster Horizontal Thrust (increases speed and flight time)

FCS

INBLUE (400 lock speed but shorter radar and lock ranges great for fast moving enemies)
063AN05 (200 Lock speed medium lock and radar range, highest ECM resistance)

Generator

GAN02-NSS-G (High output, capacity, very high KP output for primal armor, and it is fairly light)

Thrusters

Main: Duskaror-Corb (not the fastest but it is quick, light, and has very good horizontal consumption)
Back: 03-Aaliyah/B (not the fastest for regular flying but very good quick boost and decent energy consumption for regular flight)
Side: AB-Lahire (fast, good consumption, good quick boost, and light)
OB: KRB-Lahire (light, decent speed and consumption, one of the better Assault Armors)

Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

1000 kills (20 points): Achieved 1000 kills.
1000 wins (20 points): Achieved 1000 wins.
10000 kills (40 points): Achieved 10000 kills.
10000 wins (40 points): Achieved 10000 wins.
2000 kills (20 points): Achieved 2000 kills.
2000 wins (20 points): Achieved 2000 wins.
3000 kills (20 points): Achieved 3000 kills.
3000 wins (20 points): Achieved 3000 wins.
4000 kills (20 points): Achieved 4000 kills.
4000 wins (20 points): Achieved 4000 wins.
5000 kills (20 points): Achieved 5000 kills.
5000 wins (20 points): Achieved 5000 wins.
7500 kills (20 points): Achieved 7500 kills.
7500 wins (20 points): Achieved 7500 wins.
AF Answerer (20 points): Defeated AF Answerer.
AF Cabracan (20 points): Defeated AF Cabracan.
AF Eclipse (20 points): Defeated AF Eclipse.
AF Great Wall (20 points): Defeated AF Great Wall.
AF Jet (20 points): Defeated AF Jet.
AF Land Crab (20 points): Defeated AF Land Crab.
AF Soldios Orbit (20 points): Defeated AF Soldios Orbit.
AF Stigro (20 points): Defeated AF Stigro.
AF The Spilit of Motherwill (20 points): Defeated AF The Spilit of Motherwill.
Arena (30 points): Completed the arena.
Arena Rank 10 (20 points): Ranked in the top 10.
Arena Rank 20 (20 points): Ranked in the top 20.
Chapter 1 (20 points): Completed Chapter 1.
Chapter 2 (20 points): Completed Chapter 2.
Chapter 3 (20 points): Completed Chapter 3.
Class A (30 points): Promoted to Class A.
Class C (20 points): Promoted to Class C.
Class E (20 points): Promoted to Class E.
Ending 1 (40 points): Completed story(1 points).
Ending 2 (40 points): Completed story(2 points).
Ending 3 (40 points): Completed story(3 points).
Hard Difficulty (20 points): Completed all Hard Missions.
Mission Rank S (30 points): Achieved Total Mission Rank S.
Mission Rank SS (40 points): Achieved Total Mission Rank SS.
Normal Difficulty (20 points): Completed all Normal Missions.
ORCA Arena (30 points): Completed ORCA arena.
Ranker (40 points): Promoted to Ranker.