Duraludon VMAX

If my opponent has Duraludon VMAX with the "Skyscraper" Ability in play, when I use Inteleon VMAX's "G-Max Spiral" attack and choose to return the only Special Energy card attached to Inteleon VMAX to my hand, does "Skyscraper" prevent the damage or not?

The choice to remove the Special Energy card is made first, but then damage is done and finally effects of the attack. So removing the Special Energy card is an effect that doesn't happen until damage has been done and therefore blocked by Skyscraper.

If I have an Alolan Raichu with Speed Energy attached or a Starmie with Wash Energy attached, if I use their "Electro Rain" or "Multishot Star" attacks and discard those Special Energy cards would it get through Duraludon VMAX's "Skyscraper" Ability or not?

Because you don't know how many targets to select until you discard all the Energy, the process is to discard the Energy first, then choose which Pokemon take damage, and then apply damage. Since for those particular attacks the discard happens first and THEN damage is applied, as long as there are no other Special Energy cards attached to Alolan Raichu or Starmie the damage would not be blocked by Skyscraper.

If I use Mawile's "Tempting Trap" attack to place an effect on the Defending Pokemon where it takes +90 more damage from attacks on my next turn, what happens if I use Duraludon VMAX's "G-Max Pulverization" attack on my next turn? Does it still do the +90 damage or not?

G-Max Pulverization says its damage isn't affected by any effects on your opponent's Active Pokemon, so the extra +90 damage would not be done. Bad move dude...