I have this same M Charizard EX, as well as a Torkoal:
They came from some kind of lottery set, with seven different plastic keychain cards, alongside a regular-sized cardboard SNP Pikachu.
Here are two old threads that mention them as well, and also show a Ho-Oh EX:
Unfortunately, the image I linked of all seven cards is broken, and I’m unable to find it anywhere.
EDIT: Here is also a sold listing for the Ho-Oh on Mercari:
Where the seller mentions:
Here two more sold listings, for a Mega Charizard:
and Mega Gardevoir:
EDIT 2:
Found some more on this website where someone shows their collection items: https://muuseo.com/Misokatsu/collection_rooms/11
Gardevoir and Ho-Oh again:
as well as Mewtwo and Dedenne:
EDIT 3:
Found another sold listing with Torkoal and Gardevoir, but also the packaging of the Pokémon Center:
At the top it mentions:
Googling for that, finally gets me the picture again that I posted way back in that old E4 thread:
And now we also know Wobuffet is the missing seventh card:
Here an unsold listing for one of those:
EDIT 4:
And thanks to this research, I’ve also been able to find cheap unsold listings of the five keychain cards I was missing to have all seven of them soon. 
Greetz,
Quuador