Tbf the Dream Warriors were a group of traumatized kids whose powers were only effective for as long as they believed in themselves, ie they could be severely compromised by Freddy scaring them. In contrast Shark Boy and Lava Girl’s powers are actually real and cannot be dampened by Freddy’s mind games, plus SB & LG are actual experienced, professional super heroes who have taken on threats just as tough as Freddy.
How about the fact that they threw hands with Mr Electric, a being powerful enough to create tornadoes in the real world?