If Fire is GMing this as if everything was the same up to the Decimation as in the comics; then Psylocke kept her powers (in fact, courtesy of her older brother, she got some more).
In the Decimation, roughly 90% of mutants lost their powers. Those who kept them do not get new powers (except for what I say below), and those who lost them (except for what I say below) do not get new powers.
Why do I say there's exception? Well, for a time before the Decimation, some mutants have been getting new powers, or expansions upon their new powers, due to secondary mutations; apparently natural ones. For example, Emma Frost, on top of her original psychic powers, got the power to transform herself into living diamond; while Beast mutated further and became more catlike; stronger, more agile, etc; Angel got the new power of healing others with his blood; just to cite a few examples.
Some mutants who lost their powers received new powers, but those are counted cases, and they're mostly undesirable or uncontrollable iterations of their own powers, granted by sources like Terrigen Crystals, Apocalypse's bioengineering. The luckier ones, members of the latest incarnation of the New Warriors, got gadgets to simulate powers to continue fighting crime.
This is a list of mutants who kept their powers. A coloquial designation is The 198; because 198 were identified by the US government after Decimation. It does not mean there's only 198 mutants left with powers; there's more, but not too many. 200, 300... where once there were millions.
