reptile is very hard to stop, but with liu i think its possible, the fireball pressure should beat out his gravity balls, and his spit can be ducked, just gotta watchout for his OH leap and 6 frame slide... don't know if u can consistantly but when he tries to gap close with that leap, you can DB2 armor to launch him right back out before he fully lands. just note that your B1 will not stop his slide and B3~DB4B
id say you would have to keep him out with liu.. johnny on the other hand i think u should be able to pressure him out.. don't you have some ex link you can add some push back to bait the F21 setup? and i think you have faster walkback with johnny than reptile?
kinda like the kotal sonya match we had... dat walk speed with sonya was dope.