Last Pokemon I caught was a Lv. 19 Sigilyph with an ultra ball.
I planned on training him up to help me in my mission to defeat the Elite 4. Halfway through training him, I thought "I'll take on the Elite 4 again" (Having lost a few times already) and what do you know I ended up beating them, didn't even need Sigilyph
I'm still going to train him up though, pretty strong Psychic type.