[TokuChris]

The History of the MMPR Green Ranger Power from the show
Rita Repulsa had the 6th Power Coin, which was the Dragonzord coin. She bestowed it upon Tommy and with the Sword of Darkness, used it to control his mind. Once the sword was broken, the spell over Tommy was also broken, and he joined the other Power Rangers.

Rita devised a plan to use the Green Candle, which had the essence of the Green Ranger powers in it, to drain away Tommy's power. Jason was unable to stop the candle from burning, so the only way they could save the power was to transfer it and make it "inactive", thus Jason getting the dragon shield power up. The Green Candle extinguished itself but the powers remained.

When the Power Rangers handed over their power coins to save their parents, Zordon infused the Green Power coin with his own energy, revitalizing the power on a temporary basis. Lord Zedd arrived and created monster after monster to absorb the power. He eventually sealed it in a crystal and was going to use it to create his own Dark Rangers ... but Tommy broke the crystal, restoring a little of his power, which he used to save the other Power Rangers. At that point, the Green Ranger powers were gone.

However, Rita created the Wizard of Deception, who created a clone of Tommy and, with Rita's magic, was able to re-create the Green Power Coin. Thus, Green Ranger fought White Ranger while the others were trapped in the past. However the clone eventually realized he was fighting on the wrong side and joined forces with the others. Rather than stay in the present, he chose to stay in the past, and still had the Green Ranger powers. Thus, the Green Ranger power still exists, it was just "in the past".

Why there's silver on the Green Ranger helmet
During "Dino Thunder", Doug Sloan decided to have a throw-back Tommy episode where he had to fight the previous incarnations of himself. Doug explained on Ranger Board the suits - the Zeo suit was intact and fine. The White Ranger suit was a stunt suit, hence why the shoulders were falling off half the time ... it wasn't in the best of shape. The Green Ranger costume had to be completely re-created. The helmet was given a silver lining on it. During Gokaiger, TOEI either re-created or had stored the Green Ranger costume, so no worries. When TOEI sent over costumes for Super Megaforce, Saban probably took an inventory of what suits they had and what suits they'd need - seeing the Disney suit, they probably decided they didn't need the TOEI Green Ranger costume, and thus, Tommy wears the Disney suit.

I hope that makes sense