They are the second games in the PokÃ mon series , and increased the number of PokÃ mon to 251 . With the introduction of PokÃ mon breeding , PokÃ mon are assigned to one or two breeding groups . When a male and female PokÃ mon that share at least one breeding group are left at a PokÃ mon Daycare , they may produce an egg , which will hatch into a young PokÃ mon. .