Metallic Gains is used more for draw than attacking, but 20 for two on a Stage 1 is weak, even with the new basic Metal. I think 30 damage would be fine for that attack.
Regarding the wording, it should be "3 or less". Other than that, good.
Total Discharge is Totally Broken. The attack only requires one Metal. I wouldn't even need to run Lightning in my deck, 90 and discard one is nuts, especially on a Stage 1.
Wording on it is perfect, though.
Why don't you use a normal holosheet?