Probably been said multiple times
but...
I would have one shot his Hydreigon with my Emboar with Hammer Arm but it missed, Hydreigon knocked it out with a Surf. Annoyed I revived Emboar and on its second time it tanked the Surf and took Hydreigron with a Hammer Arm. The fight in BW2 went better as Hydreigon didn't know surf and instead had Rock Slide which Emboar was neutral do (kind of just realized this, they pretty much nerfed his Hydreigon in BW2. In BW it knew all Special attacks and had a wide coverage, but in BW2 they gave it all Physical attacks, a Life Orb (which while increasing its power, meant it would faint in a number of turns on its own if you're willing to wait for that to happen), and not as wide as a type coverage).
I see nobody have brought up
Cooltrainer Jennifer from Ruby/Sapphire. You walk along with your slightly underlevelled Pokémon, then BAM! A trainer! Oh, she has only one Pokémon? Milotic? That's cool...
...five minutes later, it's not cool anymore. I rushed a little too much through Sapphire, and Jennifer was the first trainer to beat me. That Milotic took everything I threw at it, Recovered back the damage, and confused me with Water Pulse until my entire team was down. I felt so pathetic afterwards.
Sorry for responding to an early post but it just caught my eye.
I think I remember her! There was this one trainer with a Miltotic in Sapphire with a Miltotic. Back then I mainly used by starter which was Blaziken and I thought "I've beaten other Water-types before. TASTE DOUBLE KICK". Of course, Milotic's Defense is huge so it didn't do much so my Blaziken soon fainted without much trouble. Of course this left me in trouble as all my other Pokemon were severely underleveled. However I had hatched the Wynaut Egg and evolved it to Wobbuffet and taught it Destiny Bond. Wobbuffet survived a hit do to the sheer amount of HP it had, got odd a Destiny Bond, and next turn when she knocked out Wobbuffett she knocked out her Milotic. Cheap way to win? Sure, but hey she knocked out my Blaziken who otherwise blazed through everything else in the game (and yes, as soon as Wallace sent out his Milotic I did the same thing).
My revenge awaits in ORAS, for this time I'll be starting with a Treecko...
The WTF Sky trainer is one of the beach on Route 8. His pokemon are level 28 when the others trainers are level 18 ?
I was caught by surprise during my first Sky Battle. I found my first one late in the game, I had a Charizard by then. I thought I would be fine since I had a Charizard and Quacklin' the Farfetch'd. Sky Battle starts and I only have my Charizard with me. I later learn not all Flying-type Pokemon can participate in Sky Battles, only the ones who are visually flying. TAUROS MULCH! I still won the battle, but it was a bit annoying, especially now since Quacklin' is my FLYING POKEMON.