Here is the full list of all 49 Chromehounds achievements worth 1,000 gamerscore.
Scout experience level maxed out
Defender experience level maxed out
Soldier experience level maxed out
Sniper experience level maxed out
Commander experience level maxed out
#1 in total conquest pts for period
H. Gunner experience level maxed out
#1 in average seasonal fame at end
Stay w/ same nation for 3 seasons
#1 in total fame for a given period
#1 in avg total fame for a given period
Destroy unidentified enemy weapon
Successfully revive affiliated nation
Deploy to every Battlefield once
#1 in seasonal conquest points at end
Win 10 times when outnumbered
#1 in seasonal fame at end
Top marks in every Story Mode mission
Complete all missions in Story Mode
Complete H. Gunner arc in Story Mode
Complete Commander arc in Story Mode
Destroy enemy HQ and win 100 times
Deploy on hover Chassis 50 times
Travel total of 1000000
Complete Scout arc in Story Mode
Deploy total of 300 times or more
Destroy enemy HQ and win 50 times
Deploy on wheeled Chassis 50 times
Deploy on multi Chassis 50 times
Deploy on treaded Chassis 50 times
Deploy on inverse Chassis 50 times
Own 1 of each part (except DL parts)
Affiliated nation wins Neroimus War
Deploy on bipedal Chassis 50 times
Affiliated nation destroys another
Secure COMBASs total of 300 times
Wipe out enemy and live 100 times
Destroy total of 100 enemy HOUNDs
Complete Defender arc in Story Mode
Win a total of 100 times or more
Complete Sniper arc in Story Mode
Attack opponent first 30 times
Destroy 50 or more enemy HOUNDs
Secure COMBASs total of 100 times
Win 5 times w/o attacking enemy
Return alive 10 times or more in a row
Complete Soldier arc in Story Mode
End 5 times in a row w/o killing enemy
Donate to affiliate nation 1 times