Since we've given Samus the abilities to shoot while crouching and morph in midair from Metroid II, we might as well complete the set and also let her shoot downward in midair, another ability introduced in that game. Morphing in midair would be down by pressing Down twice, and of course, this would be disabled by turning on Classic Samus. EDIT: Also, the behavior of the Ice Beam was changed between Metroid and the later games: Metroid: Shots alternate between freezing and damaging (it takes twice as many shots to kill an enemy) Later games: Every shot does damage, but enemies will only die if shot when frozen, so the shot that freezes will never kill (it takes one extra shot to kill an enemy) Perhaps SMBC could use the new behavior, but switch to the old one when Classic Samus is on? EDIT 2: Since Samus starts with the Morph Ball in some Metroid games (including Metroid II), she could start with it in SMBC, and get bombs as a power-up. This would make it easier to get past the later Bowsers without any power-ups (currently a problem) by letting you roll under him when he jumps.