y u gotta ninja me
If a new Pokemon character gets in, Gen 5 is also likely since there's no representative.
The reason Lucario got in is 'cause he was one of Gen 4's mascots since he was one'a the few revealed prior to Gen 4's release. The fact he was popularized by the movie also helped his chances immensely.
... Also, Sableye ain't notable. At all. Mawile and Sableye's relation as a related pair'a Pokes is also just that; they're related, not intertwined at all outside'a stats and typing. Both'a 'em wouldn't happen to represent Gen 3. Ever.