Each basic Energy card attached to Ditto provides every type of Energy but provides only 1 Energy at a time.
Attacks
Copy
Choose 1 of the Defending Pokémon's attacks. Copy copies that attack. This attack does nothing if Ditto doesn't have the Energy necessary to use that attack. (You must still do anything else required in order to use that attack.)
How much is Ditto #51/144 worth?
Ditto #51/144 is a Common card from Skyridge (2003) — today it trades at roughly $92.03 ungraded. Across the 2 printings we track, copies run anywhere from $93.38 to $1,009.48 depending on the version you're holding.
Grading changes the math on this one: a PSA 10 is valued around $1,185.88, roughly 12.9x the raw price, while a PSA 9 sits near $250.00. 201 copies have been graded to date, and 33% of them came back a 10 — worth knowing before you pay grading fees.
We update this valuation every night from live market data and verify it against real completed sales — see the chart above for how Ditto has moved over time.