My Platinum's doing great lately. I've missed using her after EX. Been having a lot of success lately against locals and online. It's just ApolloJoe that I can't beat consistently with her. Probably Roebear's Carl too if I ever get to try that matchup. The Carl matchup is tough for her.
I guess I already kind of do that with Platinum's 3C. Although that's more a case of catching people who thought I ended the string early versus creating a situation where I can outmash them.
I guess that's a frame trap example, but that's only if the 3C was a counter hit.
Basically there are two ways to do frame traps. One would be the example made earlier with plus frame moves. As Terumi, you'll do something like 2AA 5B, then dash and 2A. If you do it right, the opponent could get CHed.
The other is by delaying your strings. Let's say I do Platinum's 5B into 5C. If I press it right away there isn't a gap and it's not going to open them up. The opponent can't mash anything in between. But if I do 5B (pause) 5C, there's just enough time for them to stick a move out, but not enough time for it to come out fast enough to hit you.
Doing something like 5A 5B 5C 3C 236D blockstring as Terumi isn't going to do you any good. All that does is put you on disadvantage and won't open them up since they can't mash anything out in a solid blockstring.
In other words, you'll want to end gatlings early so you can stay in at times and not just autopilot blockstrings. Afterwards, you'll get familiar with knowing when to either go for a throw, high/low, or a frame trap.