Hoopa

For Weavile's "Evil Admonition" attack, can I count Pokemon in the discard pile with Abilities too, or just the Pokemon in play on the field?

In this case the phrase "your opponent's Pokemon" refers to the Pokemon in play on the field, not to your opponent's Pokemon cards in the discard pile or elsewhere. Generally when referring to "your opponent's Pokemon" it means in play unless another specific game zone (like the Discard Pile) is mentioned; if they don't specify a zone, then "in play" is assumed.