@ yo-yo holla
now some of this info is repeated from this thread, but i'll try to make things a bit more easy to understand.
roger rush: this move makes a great oki, that is, knock your opponent down with 236k~P or 2D, set the yo yo behind the opponent, roger rush. When your opponent gets up he is forced to block roger's fists. this buys you time to follow up with a high and low mix up. run in and do 2k, jump at them, land 2k, IAD j.k, j.p, j.k. j.s land, 2k, 5s© into whatever knock down of your choice.
using roger rush outside of oki can be followed with the same mix ups. the general way i use it is: yo yo set behind opponent or he has been hugged, 5s(far), roger rush. you can add some pressure strings and before you do the 5s, but it works the same. now let me warn you about this, your opponent can actually jumpout of this before the roger rush hits. but if you got the fear on you will be okay. use call back instead of roger rush sometimes, because if your opponent jumps, they can still get hit by the yo yo. with that they won't try to jump out as much
razor roger: This is generally used for lockdown, to get your opponent right where you want them. if you set the yo yo, and it doesn't quite make it behind your opponent, razor roger is one of the options you can use. setting this in between you and your opponent pretty much sets a wall. he has to try to jump over it or wait for it to go away. if he jumps at you, anti air him!!
here is a little trick that i use from time to time. 4 yoyo set, super jump, FDC roll, FDC roll then delay, or air dash, razor roger. the neat thing about this is that you will be so high off the screen, that they won't be able to see where they yo yo goes. and then they will be surprised to find that the yo yo was right next to them when they had no clue at all. Be careful with this though, because some opponents can counter you when you are in this state. zappa, with raoh, or if he hits you with the three ghosts one of the pots can hit you, chipp can teleport right in front of you regardless of height, roboky can shoot missles up, and some other characters that i can't think of atm.
another this is after a you do the air bnb to a cornered opponent, set the yo yo to the opposite side of the corner, razor roger or call back. chances are, the opponent is gonna try to tech out of the corner, and when he does he is gonna be forced to block roger. another option would be FDC roll , air throw their tech.
roger hug: this move makes a pretty good oki, and its also good for when your opponent gets into defensive mode. lets say you are both backed into opposite corners, you do a yo yo set into roger hug, now the only way your opponent can avoid it is by double jumping except for some characters who can double jump and still air dash like dizzy, milia and chipp has triple jumps. for everone else, this gives you the opportunity to dash in and poke him 6s or do whatever else. if they block it well, they just got hugged which makes it easier for you to get in because you got the yo yo on him. when your opponent has been hugged, and is running towrad you, never call out roger, because he will be left behind your opponent. instead, do call back or wait for your opponent to get within stricking distance, put them in block/hit stun and do whatever you want with the yo yo.
when you said blocking, i'm not sure if you mean when your opponent is blocking or when you are blocking so i'm just gonna assume the latter. When you are blocking you really just need to find holes in their pressure. use, 2P, 2D, if your opponent jumps at you use 6P, if your opponent likes to start with low hits use 3P. IBing and FD blocking help out alot with this.
Hope i was able to help :D