Any Trainers (Items, Stadiums, Supporters) or any "Trainers" meaning "just Items" because during the time cited Supporters and Stadiums were spun off into their own card Type?
I don't trust the-powers-that-be because
Lysandre's Trump Card being a problem was pretty obvious. As severe a problem? Perhaps not... but then there is my disappointment with the direction of the game over the last several years. It seems like we are reliving so much of the game's past history with the-powers-that-be repeating mistakes that they should have learned from when they happened for the first time... which sometimes means going all the way back to
Base Set and sometimes includes making the same mistake more than once before. ^^'
Generic evolution acceleration has always been potent and only not problematic when big, Basic Pokémon are. Problematic, that is.
There is a hypothetical "sweet spot" but it requires work that isn't already being done, like making Evolving Pokémon good enough to help support the Evolution line (so you don't need a super-special-awesome end Stage to compete) and giving you reason to
not skip over intervening Stages.
Broken Time-Space for
just Grass-Types will only work out if Grass-Types are otherwise pretty weak and/or everything else is stupidly strong. Of course, I still don't expect anything else to be banned anytime soon: we'll utter domination in several medium level events or at least one high level ("high" meaning Worlds, U.S. Nationals, something major in Japan, etc.).