Genders didnt exist except for nidorans in gen 1, so its not possible to breed.
In gen 2, the breeding rate is like this:
Same OT and species: 0.14% per step "It's friendly with 'other Pokemons nickname'"
Different OT and species: 0.1% per step "It's friendly with 'other Pokemons nickname'"
Different OT, same species: 0.19% per step "It appears to care for 'other Pokemons nickname'"
Same OT, different species: 0.04% per step "It shows interest in 'other Pokemons nickname'"
For some reason, if the two Pokemon have the same defence IV and special IVs that are different by either 0 or 8, they will NOT breed and the daycare man will say "It's brimming with energy" instead.
Generation 3 and Up:
"They would rather play with other pokémon, though."
Your two Pokemon are incompatible for breeding; they do not belong in the same egg group, are the same gender or cannot breed at all (usually legendaries).
"They don't seem to like each other that much."
They are different species and are from the same original trainer, this means they will breed, but with a 20% chance of producing an egg every 256 steps.
"The two seem to get along."
They are different species and original trainer, they have a 50% chance of making an egg every 256 steps you take.
"The two get along very well!"
They are same species and different original trainers, and will have a 70% chance of an egg every 256 steps.
Hope I helped!