>>49858730Any Pokemon whom you are willing to put in the time and effort in, whom you are willing to treat with love and kindness and accept as they are.
There is no wrong option, there are ones that are more or less likely, and some Pokemon that would be more or less naturally inclined, but just like with people, it depends on the individual Pokemon in question- except any romance between two intelligent species that have so many differences and can still connect in that way is more pure by default.