Mass Effect: Andromeda

You can get this achievement in the single player campaign by resetting your character skills in the Med Bay on Tempest. You need:
- at least 234 skill points available for your character (LVL 46);
- 11 000 credits - if you used Respec Station before, you will need more money because price gets higher every time (20, 520, 1020, 1520, 2020, 2520, 3020 credits etc.). If you don't have money, you can do manual save and then reload after each profile has been fully unlocked (credit to Greenshell48 & MrkDhn10).

Go to the Med Bay on Tempest (lower level). When you are in the Med Bay, turn left. You will find there Respec Station, choose Ryder. Advance one profile to level 6 by spending points in the required skill tree (Combat, Tech, Biotics). When you are done, reset your character again and do another profile. Repeat this process until you had all 7 profiles maxed at least once.

Profiles - spent skill points required for LVL6:
- Soldier - 232 skill points in Combat
- Engineer - 232 skill points in Tech (you need to have the Remnant VI power unlocked)
- Adept - 232 skill points in Biotics
- Sentinel - 116 skill points in Tech and 116 skill points in Biotics
- Vanguard - 116 skill points in Combat and 116 skill points in Biotics
- Infiltrator - 116 skill points in Combat and 116 skill points in Tech
- Explorer - 78 skill points in Combat, 78 skill points in Biotics and 78 skill points in Tech.

This is the way to unlock using Multiplayer.

Look to the other guides if you are interested in the single player way to unlock this achievement (honestly single player method looks way easier).

Here is the guide:

Use characters that earn experience toward the same stat and level the bonus stat to Level 6. Health Regeneration Cap and Max Shields have the most characters to play. Health & Shield Regeneration Delay Reduction has no Ultra Rare Characters to play. But the best Platinum Bonus Stat group is Health Regeneration Gap because it has Human Juggernaut, Human Artificer, Human Infiltrator and Asari Adept which are all Platinum viable.

If you search for a quick match you might be able to drop into a game that has already started which means it will finish sooner and XP is gained faster.

Attaining a Level 1 Bonus Stat requires leveling one character to Level 20. A Level 2 Bonus Stat requires the amount of XP to level 2 more characters to Level 20. I estimate that to gain a Level 6 Bonus Stat you will have to gain enough XP for 21 characters to reach level 20. Resetting characters is not necessary because XP is still gained toward the Bonus Stat when the character is at level 20.

More experience is awarded the higher difficulty of the match where Gold (or Platinum now available) has the highest XP earned per match.

Use the Apex Missions with Experience Point bonuses to help with the grind.

See your Bonus Stat progress:

Connect to the EA Servers and enter the Multiplayer menu. Enter sub menu Prestige and choose the menu item Bonus Stats. This is where the bonus stats are located.

See a character's Bonus Stat:

In the Multiplayer menu, select Change Character and while a character is highlighted the bonus stat should be visible in the bottom right corner of the screen.

List of Bonus Stats:

All Power Recharge Speeds
Health Regeneration Cap
Max Health
Max Shields
Health & Shield Regeneration Delay Reduction

"Experience points gained in a match get applied to the current character and its bonus stat." -- from the Bonus Stats menu

Level Requirements (Reach the XP amount):

Level 1: 2,127,000 - Reward: (+1.0%)
Level 2: 6,381,000 - Reward: (+2.0%)
Level 3: 12,762,000 - Reward: (+3.0%)
Level 4: 21,270,000 - Reward: (+4.0%)
Level 5: 31,905,000 - Reward: (+5.0%)
Level 6: 44,667,000 - Reward: (+6.0%)
Level 7: 59,556,000 - And it keeps going!

Playing with the following characters will work toward the noted bonus stat:

All Power Recharge Speed - 8 to level
Human Engineer - Common Class
Krogan Mercenary - Rare Class
Angara Insurgent - Rare Class
Asari Huntress - Rare Class
Angara Avenger - Ultra Rare Class
Angara Exemplar - Ultra Rare Class
Salarian Operator - Ultra Rare Class

Health Regeneration Cap - 9 to level
Human Adept - Common Class
Human Infiltrator - Common Class
Asari Adept - Uncommon Class
Salarian Infiltrator - Uncommon Class
Human Artificer - Rare Class
Human Juggernaut - Rare Class
Krogan Gladiator - Ultra Rare Class

Max Health - 5 to level
Human Vanguard - Common Class
Human Commando - Rare Class
Turian Havoc Trooper - Rare Class
Human Kineticist - Ultra Rare Class

Max Shields - 9 to level
Human Soldier - Common Class
Turian Soldier - Uncommon Class
Batarian Scrapper - Rare Class
Human Guardian - Rare Class
Turian Agent - Rare Class
Batarian Vanguard - Ultra Rare Class
Asari Duelist - Ultra Rare Class
Salarian Architect - Ultra Rare Class

Health & Shield Regeneration Delay Reduction - 5 to level
Human Sentinel - Common Class
Asari Sentinel - Uncommon Class
Krogan Engineer - Uncommon Class
Krogan Vanguard - Uncommon Class

Even when your character is maxed out at level 20, the experience points gained in a match will get applied to the bonus stat of the current character.

Boosters
Experience Enhancer I - Increase Experience Gained by 25%.
Experience Enhancer II - Increase Experience Gained by 50%.
Experience Enhancer III - Increase Experience Gained by 75%.
Experience Enhancer IV - Increase Experience Gained by 100%.

Difficulty Experience Average
Bronze: 55K Full Team (??? Solo)
Silver: 75K Full Team (??? Solo)
Gold: 100K Full Team (??? Solo)
Platinum: ??? (100K Solo)

APEX Mission Modifiers
Increased Rewards I - Completion rewards increased +60% xp and credits.

Check out this video for more ways to earn bonus points. Using this glitch will gain the bonus XP toward the starting character​ [EXPLICIT LANGUAGE]:

The Achievement unlocked for me as expected after 9 months of casual play.