A shiny Cyndaquil at Level 5, assuming no EV investment, will have either 18 or 19 HP. It is 18 when the HP DV is 0 and 19 when the HP DV is 8. If 252 EVs (the maximum) are allocated to HP, the final stat will be at 22 for either DV.
Source: Pokemon Showdown's teambuilder, checking the validity of DV combinations until they were successful, and recording the numbers.