heres a code by Baka_Kyuubi84 of kodewerx.net:

::Reduce honey tree timer to 0 at valley windworks
:::Press L+R then walk through a door or fly. Change X to 00-05 to get different pokemon.
94000130 FCFF0000
62101D40 00000000
B2101D40 00000000
10007FD4 00000001
00007FD8 0101010X
D2000000 00000000

and heres the one with munchlax!:
(L+R)
94000130 FCFF0000
62101D40 00000000
B2101D40 00000000
10007FD4 00000001
00007FD8 02020202
D2000000 00000000