O Gumshoos, one of the band members of the Wyndon national parade got sick, and you can take his place. Which will be you Pokemon and Instruments
Note: This is based on your birthday, im NOT gathering information
To avoid confusion, YOU play the instrument, not your Pokemon
Jan - Clarinet
Feb - Glockenspiel
Mar - Tenor drums
Apr - Bass drums
May - English horn
Jun - Cornet
Jul - French Horn
Aug - Trombone
Sep - Snare Drums
Oct - Piccolo
Nov - Flute
Dec - Bells
1 - Claydol
2 - Growlithe
3 - eevee
4 - gloom
5 - Gothitelle
6 - Kirlia
7 - Scrafty
8 - Fraxure
9 - Xatu
10 - Blipbug
11 - Weavile
12 - Inteleon
13 - Hitmontop
14 - Sandaconda
15 - Butterfree
16 - Golisopod
17 - Charjabug
18 - Togedemaru
19 - Bunnelby
20 - Cubchoo
21 - Pinchurchin
22 - croagunk
23 - Shellos
24 - Dragapult
25 - Cleffa
26 - Arctovish
27 - reuniclus
28 - Drapion
29 - Vulpix
30 - Conkledurr
31 - Delibird
Ex: I take a Cubchoo with me while playing snare drums