Meta Knight seems like a character who can potentially be very good if you know how to use him yes. I'd also recommend Ike, Ike looks really to be really powerful if you get good with him. Also, Ness is very hard to use but when you get very good at him, he totally dominates too like Ike.
Olimar is very good yes. He has very bad recovery but that doesn't matter, just the fact you keep throwing Pikmen then run means you'll always do tons of damage to the other guy while barely taking any yourself. In otherwords, it feels like Olimar seems to be a sorta broken character like that. Especially the white Pikmen, they're like insta-KO.