Although restricted to just damaging EX Pokémon, Hawlucha's damage output is fantastic (plus it has free retreat and can be easily searched with a Level Ball. another, all-time favorite of mine for the Expanded format is Landorus EX. Its Hammerhead attack's 30 (possibly 50, 70 or 90 with an attached Muscle Band, Strong Energy and/or Fighting Stadium)-30 damage output for just F energy cost is arguably one of the best (if not the best) attack in the format.
Relative to Psychic Pokémon, Wobbuffet can inflict lots of damage depending upon the amount of damage on the defending Pokémon for just P energy cost if a Dimension Valley Stadium is in play; PLUS, Wobbuffet's Ability cancels non-Psychic type Pokémon's Abilities when it is active. Very solid. Mewtwo EX (Expanded format) is another time-proven, "hall-of-fame" type Pokémon, IMO. It's X-ball attack is fantastic, especially since it only needs CC energy. Lastly, I like the Crobat line as techs in certain decks to provide some extra damage drops and enable KOs.