hey sorry for the late response.
as for grabbing, your gonna have to be a little quicker with you tech chase. there is a short window of opportunity after a tech where the opponent is vulnerable.
if not that, since you know he will dodge, just wait for him to dodge and then grab him.
also shield grabbing is the classic way to get grabs if you have the opportunity.
also with fox, you can simply shffl a dair, then grab. and against heavier characters you can even better, shffl dair, waveshine, grab. thats another benefit of using the dair, it doesn't ever knock any character down, so you can immediately grab or shine afterward. and if you get the timing down, you can dair a shield, and shine before they can shield grab you. falco can do that too.
rolls may work on the one guy, but if he's any good, eventuall he'll figure it out, and if you ever play other people who are good they'll figure it out immediately..