About atk/def/sta stats.

Hey everyone, what does the advanced stats mean?
For example, a Rhydon's max atk/def/sta is 222/206/210, if I have one with (15/9/15), it means when the Rhydon power up to max, the atk/sta will be 222/210, but the def will be 206*(9/15). Is it right?
Btw, if it means this Rhydon is only good as an attacker (to attack snorlax. I still don't have Dragonite)??
Thanks so much and have fun!