A lot of Pokemon will be more viable, including ABA and ABC mons

Details are not clear yet how expert mode will work but it looks like favorite berry mons will be much more powerful than others. So even ingredient mons might be much better if they match to the favorite berry of Snorlax. Depending on how big the buffs are AXX mons might gain a lot of value.

We will also have to see if Energizing Cheer or even Umbreon will become viable options. Ingredient Magnet and the new Ingredient Draw skill could also profit a lot.

Is there something else I am missing that might change "meta" for expert mode? The devs said themselves that they wanted to make ALL Pokemon useful.