He doesn't really use the cymbals or the kick drum in the RS battle themes for some reason, with the only drum kit instrument being the repeating "2 + 4 beat" snare for the most part. He seemed to prefer to use the timpani for the "lower" part of the percussion track in the battle themes which is a strange choice I'm struggling to understand. Some battle themes use the crash cymbal sparingly (like before the loop in the trainer battle theme, or the hand claps in the Elite Four battle theme) but not consistently. The difference between Masuda's battle compositions can be heard starkly with Ichinose's Frontier Brain battle theme which opens with fast crash cymbals and a high hat rhythm throughout with kicks introduced later. One of my ROM hack ideas is to add proper drum tracks to the Emerald battle themes just to see how it sounds.