Whenever I take my Pyra out for a spin, I generally have an engie with wrench, buff, chem balloon-side. If I'm flying a metamidion, this engie is also in charge of the mortar and can keep my balloon buffed and chem-sprayed. The other gun, the gat on my metamidion, generally takes spanner mallet buff. This let's them keep the gat repaired, and pre-buffed at all times. If there are quite a few flamers on the other team, I'll swap out my top-right engie to have wrench buff chem as well. This way the guns stay repaired, usable, and prebuffed at all times.