I bought all DLC Characters, only use Roy and Lucas though. Having a larger roster means more variety, which is a good thing.
Roy isn't really that cheap. Just a few things I found out with him though:
With most characters he can D-throw -> Jab -> F-Smash in the early percentages.
If your opponent doesn't DI correctly and it's a fast falling character then you can D-throw -> Jab chain grab. I got to 0% to about %55-ish doing this. Just DI-ing will save you here though, that Sheik player sucked.
You can short-hop fair and use any special right as you land, and have no landing lag what so ever. It's an amazing approach, shorthop fair into dancing blade works alright, although I prefer into up-b. If you have a really aggressive opponent, short hop fair into counter works wonders, but you really need to read their style.
If your opponent is in the air, fair to uair works really good as well, the uair comes out faster than anyone would expect it to.