>>28848593Why are you asking Smogonfags to defend it when it's a universal thing?
Anyway, Species clause exists because without it battles would be even less diverse than they are now. Can you imagine how broken it would be to have more than one Manaphy on your team? One of the downsides of many Pokémon is that they're limited to one set. Now you can run that Pokémon and have all of its sets in your team at once. You can have a Manaphy that's Tail Glow + Rain Dance, one with Tail Glow + Energy Ball, one with Rain Dance + Calm Mind, one with HP Fire, and so on and your opponent cannot do anything to differentiate or play around them.
