Basically the entire meta right now is dominated by "cards that stay on the field": Scoia'tael Dwarves use Mahakam Defender, a Resilient unit (the wooden bar across the bottom and fist emblem on red escutcheon indicates he'll stay on the board) or Adrenaline Rush to keep a strong unit around for one round (typically Hawker Smuggler, a card that gets 1 point stronger every time the opponent plays a unit). Monsters' faction ability keeps their last unit played (non-resilient already, non-token, non-fleeting) so they typically want to play a strong unit before they want to pass, coupled with Nekkers which get placed on the board as they die, including once the round is over, and Skellige which has cards that go to the graveyard but come back on the board like Morkvarg, and the neutral card Olgierd.
To deal with specific examples, to beat Scoia'tael Dwarves, they rely on buffs to make their investment worth it (otherwise they win one round but can't maintain strength for another). Dimeritium Bomb is the best counter to them. You can also use Geralt: Igni to take out the strongest, but smart players will stagger their strength meaning it only hits one, or play a Frost effect very late in the round to negate their strength. D-Bomb, Igni and Frost also work against Nekkers. Another effective strategy is to use Manticore Venom to hit every target of the same type after they use Monster Nest, meaning any Nekkers they added to the bottom of their deck with Nekker Warrior gets put on the field, meaning less available for later rounds. And for Skellige using Morkvarg and Olgierd, if you're Monsters you can consume Olgierd. You can try to pummel Morkvarg, but 9 times out of 10 you won't have enough damage to do so, so you just ignore him.