Ice climbers without a doubt have the best grab/throw game in brawl. When every single character is constantly living in fear of getting grabbed, and their whole matchup changes just to avoid getting grabbed (as people have mentioned) you know that their grabs are truly powerful and awe inspiring. If the Ice climbers grab you, it is a guaranteed stock. Literally, they can chain grab, they can play pass with you, they can spike you out of a throw, they can smash you out of grabs, they can just pile up damage then kill you however they want. Once an ice climber has grabbed you, you can quietly set down the controller and walk away, because you know that they have just won. (speaking of which, I lost the game.)
D3 on the other hand, has a ridiculously powerful chaingrab that leads to a guarenteed hit, has some excellent and powerful throws, but is not a guarenteed death (unless you are DK, then I feel bad for you) He can get a nice chain of throws for some damage, and then kill you. He has an enormous reach with which to pull you to him where he forces you to kneel before him, then he simply curb stomps you repeatedly before smashing your stomped face with his hammer, sending you into oblivion. Aka, d-throw chaingrab to f-throw kill. D3 is excellent, with a massive grab range and a powerful chaingrab that many people fear, and which leads into kill options.
Falco is always a source of fear at low percents, because when he grabs you, he is ready to throw you down, shoot your face off, and do it over and over until he is ready to stomp you into oblivion. Something about repeated headshots bother people, so Falcos chaingrab is often feared and avoided.
Olimar has an enormous grab range, and powerful throws to all sides. Its large, fast, and deadly. However, it isn't as bad as ICs or D3, it simply causes caution rather then peeing in your pants level fear.
Ness has excellent throws to kill, but again, not a chaingrab, so simply a good option rather then the best option.
Pokemon Trainer also has excellent throws, ranging from charizards and ivysaurs huge grab range, squirtles hydro grab slide range, and the kill potential all three represent they certainly are worth mention.
Kirbys throws of course are great, due to the fact that they combo into kill moves and just look badass.
Mewtwo is of course broken good with his throws, but unfortunately they are tourney banned. D:
