Thanks for the tag. I went through your list @tccjm2 , and these are the ones missing:
Officially released regular sized cards:
- Expedition Base Set 56/165 Reverse Holo
- Unbroken Bonds 75/214 Reverse Holo
- Unbroken Bonds 75/214 Cracked Ice Holofoil (from the Battle Mind Theme Deck)
I think you’ve excluded Jumbo-sized cards on purpose? If not, these are available:
Officially released Jumbo-sized cards:
- Best of Game Rocket’s Mewtwo Jumbo
- Next Destinies 54/99 Mewtwo-EX Jumbo
- BREAKthrough 61/162 Mewtwo-EX Jumbo
- BREAKthrough 63/162 M Mewtwo-EX Jumbo
- BREAKthrough 64/162 M Mewtwo-EX Jumbo
- Evolutions 52/108 Mewtwo-EX Jumbo
- SM196 Mewtwo-GX Jumbo
And then there are a bunch of unofficial releases (misprints, Sample cards, print differences, etc.):
- Expedition Base Set 56/165 non-Holo MATCHPRINT
- WotC #4 Promo with Inverted WB stamp
- WotC #4 Promo without stamp
- WotC #4 Promo printed on Japanese printing paper
- Base Set 1st edition (3x): Thick stamp; Thin stamp; Grey stamp
Hope that helps. I would for now just focus on the officially released Mewtwo cards (considering there are only two known copies of the MATCHPRINT for example; the Inverted WB promo is worth 2.5-4k USD; and I’ve only seen the Mewtwo without stamp twice thus far).
Good luck completing your collection, and if you have any questions about the cards above, lmk. 
Greetz,
Quuador