Wailord needs entry hazards set up on the opponent's side of the field to be effective, as foes can switch around without much trouble otherwise, limiting its PP stalling abilities. Don't be afraid to use Wailord's natural bulk to switch in on threats it can wall, such as Torkoal.
A pony is not a small horse. Horses and ponies are genetically two different species. There are horse-sized ponies, and pony-sized horses, but the genetics are what tells them apart, not the size. A miniature horse, for example, is very small and looks like a pony, but genetically, it is a horse.
Really riding a 18 month pony now that is just wrong. Anon, about riding an 18 month old pony - I'm hoping I'm mistaken and not you, but pony isn't an age. A pony is a horse that will never grow taller than 14.2 hands, no matter how old it gets. Anything taller than that is considered a horse.