GP-03 Dendrobium as a Master unit with Kou Uraki's Illusionary Marksman and Cool Headed skills makes for a deadly unit. Max out these skills and the Dendrobium becomes downright beastly. Add a Beam Generator Omega and its primary weapons (Beam saber and cannon) will become that much deadlier.
For multi-lock situations, Garrod Ran in G Falcon DX is a good choice. With the right skillset, Twin Satellite Cannon can become quite cheap in EN cost, and a Raiser System will boost its attack to 10000+. How's that for devastating firepower?
well both are good, maybe he suggest me Kou because he's the ''canon'' pilot of GP03 stamen and orchis, but I can also use GP02 with Gato, that atomic bazooka attack's quite effective, however, I'll use Turn A (black history) due his high atk power and abilities (IIRC, he has 3 attacks, two makes 10k damage or so)