For an imperial trooper team you should focus on veers snow trooper shore trooper death trooper and starck. Veers is the best lead for troopers hands down though his unique zeta works under any empire lead. Shore trooper is one of the best tanks in the game and has multiple uses in raids squad arena TB and TW, he is a grind but worth it! Death trooper is again a multifaceted character with various uses but he really shines in the sith raid! Snow trooper is the real fire power on a trooper team hes fast and he hits hard, his AOE can reset it's own cool down meaning with enough critical chance you can use it every time. Starck is the new addition to the trooper squad replacing either magma or storm trooper. Starck basically improves the synergy and functionality of your entire squad and is essential for DS TB and sith raid. Don't over look magma trooper, if the grind for death trooper seems too much magma is an excellent choice as a replacement. Lastly storm trooper is not to be underestimated, shore trooper is a better tank but storm trooper can be used in any trooper team to great effect. Actually at lower gear levels having shore and storm as a double tank can keep your team alive longer.