Board Thread:Plants vs. Zombies 2/@comment-5760976-20180115141847/@comment-24024415-20180316213840
Then again, that does have the issue that your plants are all Lvl 6 and your opponent with mostly Lvl 1 with a lot of filler cards. Still, it seems the cheap (meta) plants are completely untouchable when it comes to performance with Power Plant levels on an equal level.
The best thing I could suggest to the OP's question is to level up a time period's plants and have the level advantage or unfortunately be forced to fight premium plants with their own premium plants.
More on the first point, Modern Day and Dust Lobber/Moonflower will certainly be a great asset, but Dark Ages would certainly be a good contender barring Magnet-shroom for a fast and potent mushroom armada once leveled up. Especially Puffshroom to bodyblock zombos from the lower score tiles.