Mass Effect & Mass Effect 2
Traditional krogan tactics were built on attritional mass-unit warfare. Equipped with cheap rugged gear, troop formations were powerful but inflexible. Command and control was very centralized; soldiers in the field who saw a target contacted their commanders behind the lines to arrange fire support.
Since the genophage, the krogan can no longer afford the casualties of the old horde attacks. The Battle Masters are a match for any ten soldiers of another species. To a Battle Master, killing is a science. They focus on developing a clean, brute-force economy of motion that exploits their brutal strength to incapacitate enemies with a swift single blow of overwhelming power.
This change of focus from mass-unit warfare to maximal efficiency has increased employment demand in the fields of security and 'muscle for hire'. Due to the unsavory reputation of the krogan, most of these jobs are on the far side of the law.
Battle Masters are not 'spit and polish', but they do believe in being well-armed and equipped, preferably a gun for each limb. They are callous and brutal, but methodical and disciplined. They use any means at their disposal to achieve their goals, no matter how reprehensible. Hostage-taking and genocide are acceptable means to ensure a quiet occupation with few krogan casualties.
The krogan serving with Saren's forces appear to be returning to the old style of mass attritional combat. They also work in close cooperation with supporting geth units, who fill the roles occupied by combat drones in other armies.
Biotics are rare among the krogan. Those that exist are viewed with suspicion and fear. The krogan see this aura of fear as a useful quality for an officer, and often promote them. Combat drones are other high-tech equipment are likewise in short supply.