It's good damage, but, it isn't significantly different from landing a jab with Ike under normal circumstances if the opponent still has a mid-air jump at their disposal, other than the extra pressure of having to stay in the air, basically.It's a nasty bit of damage, particularly considering you're facing Ike, and can send you at a bad angle off stage for more damage/gimp opportunities.
But this isn't related to RCO. What other kind of set ups do characters have? PT for example, since I'm quoting Reflex.
Uh...Because of SDI, Squirtle's jab doesn't do well at forcing it from the air, unfortunately. Ivysaur has a nice set-up, though--It's pretty easy to guide a N-Air into its more-or-less set knockback spike if you're just doing it to an opponent on-stage. Ivysaur gets decent-to-great frame advantage on this (anywhere from ~+5 to +16, depending on positioning) by itself due to its properties, but if an opponent has RCO lag, you would add the hard landing number to the regular frame advantage, meaning that you can combo it into pretty much anything, most notably U-Smash.