I have my doubts on the reptile matchup being 3-7. It is possible to trap him with ex forceballs. You gotta use 13 ex force ball. It jails, so you can use this off a jip. You can use 44 but that string doesn't jail. You can also do 11, 11, 11 ex force ball. At close range, there's a sweet spot where both force balls hit, and three 11s or a 13 will put you there. Unfortunately, there's no way to trap him in the corner, 13 ex force ball only works at mid screen.
I also say ermac is 6-4. You can also use 13 ex forceball, or 11, 11 ex force ball. In the corner, ermac is totally screwed. F33B3 ex force ball jails on everyone except reptile in the corner.