How Likely Is It That a CGC 10 Japanese Mewtwo Reaches BGS 9.5?

A CGC 10 Japanese Mewtwo has a moderate-to-good chance of reaching BGS 9.5, though it's far from guaranteed.
Japanese Pokemon TCG cards and pricing

A CGC 10 Japanese Mewtwo has a moderate-to-good chance of reaching BGS 9.5, though it's far from guaranteed.

HGA 7 Alakazam cards rarely receive CGC 1 grades when regraded, because such a dramatic downgrade would be exceptionally unusual.

The short answer is: very rarely. Cards graded by HGA at a 2 don't typically get submitted to PSA and jump to a 7.

BGS 7.5 grades on Solgaleo cards are moderately common in the graded card market, but they appear far less frequently than comparable SGC 5 grades when...

Pre-release Mewtwo cards do see grade improvements after regrading, but not nearly as often as collectors hope.

Lv.X Articuno cards experience higher grades after regrading roughly 15-25% of the time, though this varies significantly based on the card's condition,...

There is no publicly available data tracking how many PSA 2 Lv.X Lapras cards have been resubmitted to SGC and received a 7.5 grade.

There is no publicly available data documenting the specific success rate of SGC 9 to BGS 10 crossovers on Dragonite cards.

CGC and BGS employ fundamentally different grading standards and evaluation criteria, which is why a card receiving a CGC 1 often receives a lower...

SGC 1 graded Vaporeon cards rarely receive HGA 6.5 grades when submitted for cross-grading, though the frequency depends heavily on the specific card,...