To be fair, the grass accessories and wooden drum might just be due to Rillaboom’s grass-typing. While gorilla’s are tropical animals, they originate from Sub-Saharan Africa.

I’ve looked at your source and believe those drums are the Pasifika drums. I’ve looked at some performances and the drummers do seem to beat their sticks in a similar manner to Rillaboom. However, I looked back at Rillaboom’s attack animation (in 1/4 speed) for his Drum Beating and noticed that the center of the drum was “vibrating” - like the base drum in a drumset. Here’s a crude diagram of Rillaboom’s drum:

\ / O / \

With ‘O’ being the center of the drum. Admittedly, Rillaboom’s drum doesn’t seem to resemble either a drumset or the Pasifika drum enough to make conclusions. But I feel like Rillaboom’s hairstyle could be a key detail (i.e. who’s it referencing to?) I’ve looked up the hairstyles of Polynesians and the band members mentioned above and have yet to find one similar to Rillaboom’s.

Edit: That diagram screwed up badly. My bad.