Houndour #2, check.
Update on the Rhyhorn. Again, I have four specimens. I did not run battle tests this time (the Houndour are back at Lv.1 BTW). The natures and Potential Checks came out as follows:
Rhyhorn #1: Quirky (no boost), relatively superior potential, Defense best.
Rhyhorn #2: Docile (no boost), outstanding potential, HP best, Defense and Spoeed also good.
Rhyhorn #3: Relaxed (+Defense, -Speed), above average, Sp. Attack best, Speed also good.
Rhyhorn #4: Lax (+Defense, -Sp. Defense), relatively superior potential, Attack best, Defense also good.
#4 seems like it meets what you're looking for with the Attack IV being best and Defense also being good, but the nature boosts Defense instead of Attack. I got no natures boosting Attack. I can try again if you'd like.