k, so there is a way to RNG in gen 5 with a DSi but it is harder than the one that does not use a DSi. For you, if you are not using a DS then g4 and g5 will be about the same level of dificulty, but g5 is slightly harder.
tl;dr
you have 3 choices:
1. RNG gen 4 (slightly easier than #2 if using HGSS)
2. RNG gen 5
3. get an emulator