Depends on distance but anything that isn’t a light attack (or causes knock down) can combo into LK Shunpuu, linking afterwards is pretty dependant on distance and has to be 4 frames of startup or less.
Common options I guess would be:
s.HP xx LK Shunpuu > c.HP xx HP Shou or HK/EX Shunpuu - should work on all characters when close enough, highest damage but possibly hardest way to combo
c.HP xx LK Shunpuu > s.LK xx HP Shou or HK/EX Shunpuu - should work on all characters, probably the easiest way to combo, s.LK has the most range but c.LK can be used instead (does less damage varying on character)
c.MK xx LK Shunpuu > s.LK xx HP Shou or HK/EX Shunpuu - c.MK forces the low block but doesn’t make crouching characters stand so Shou is needed for hitting crouching opponents over Shunpuu
c.MP xx LK Shunpuu > s.LK xx HP Shou or HK/EX Shunpuu - same as above but c.MP used as a counter poke since it seems to have fairly good priorities