Will do. Sister's home sick, so not going to fester around here too much waiting to collect said sickness; will hit the showers and get out sometime before lunchtime, I think. Maybe a lunchtime gathering again?
As for Corsola, its appearance at Undella Town is in rippling water (not fishing, but Surfing into rippling water) and is found from Lv.25-60 with a 30% rate of appearance. They do learn Earth Power at Lv.53, but I have not researched if it replaces Mirror Coat on those particular Corsola. That means Lv.48-52 are the "butter zone" for catching a Mirror Coat Corsola; however, one before that level can still learn it, and you can use a Heart Scale to have a higher-level one relearn the move. Flail, meanwhile, is not learned until B2/W2.
What I can do is give this one Pokérus if you'd like.