The following are known CTRPF AR Cheat Codes for Rhythm Heaven Megamix on Nintendo 3DS (3DS).

000400000018A400.txt

[Challenge always 3 lifes (train life)]
28878001 00000003

[perfect tries always 3]
2835ED2B 00000003

[99 gold turnips (infinite)]
289270EC 00000063

[Slot1 - All Songs 100 Points*]
C0000000 00000035
0835E254 27102710
DC000000 00000004
D2000000 00000000

[Slot1 – Unlock all Songs/Perfect Rank/Art/Items]
C0000000 00000025
0835DCD4 06060606
0835EE00 03030303
0835EF14 03030303
DC000000 00000004
D1000000 00000000