Cancels and Dash
Special and Super Cancels
In regards to cancelling, normals do not gain nor lose special cancel properties based on whether they were chained or linked. So if a cr.MK is special cancellable, it will always be able to be special cancelled. However, not everyone shares the same special cancellable normals. For example, while Kairi can cancel his cr.HP, Shirase cannot special cancel any of her heavy normals. Be sure to check out the characters page to see which of your character's normals are special cancellable.
As for super cancelling, all normals can be super cancelled except for command normals that are overhead. So if you do a full chain series with no cancellable normals, you will still have a way to extend the combo by super cancelling.
You can also buffer the super or special motion behind normals as it will hit opponents that come into your buffered normal range. A lot of heavy buttons are great to buffer into some supers as they are very active and can stuff dashes and jumps.
Using Dash Momentum
One more thing to note about grounded combos is that this game has dash momentum, so if you do a normal out of a run, you'll have less push back than if you did so raw. This allows you to get combos you normally wouldn't, such as linking Kairi's cr.MP into itself, or chaining Hokuto and Shirase's cr.LK into her cr.MK.
This also applies to pressure so be mindful if you are dashing or not as the slight momentum can affect your combos. Most characters can only combo two hits of a combo at close range unless they dash and use the momentum.
