Ok, here's my concept for a Bowser's Castle stage:
http://i50.photobucket.com/albums/f339/dracomageat/bowsercast_zpscaa54ad1.png[/collapse]
It's a fairly wide stage, in terms of solid area, with grabbable ledges as any competitive player would demand and a lot of flat space. That, however, is where the normality ends. There is no offscreen fighting on this stage. What you see is what you get and the blast zones are therefore abnormally close to the play area.
Don't camp at the edges in the hopes of an easy kill though. At regular intervals, the blue Thwomps in the upper corners of the stage will shake to alert players to their imminent fall. They will not have long to move and, should a Thwomp catch them, players will take huge damage and knockback, hitting diagonally downwards such that the ill prepared will most likely either be KOed sideways or shoot down into the lava below.
The Thwomps spend less time down than up so as to prevent wall infinites going on for too long. During this time, the stage does technically have walk off ledges but they are raised above the main play area and, should a player attempt to camp atop a Thwomp, they are likely to be star KOed when it rises without warning.
So, what about the lava you ask? It's a touch weaker than Brinstar's but essentially the same. Players caught in it will most likely not be KOed off the sides but will instead have to navigate the stage's awkwardly shaped underside in an attempt to pass back up through the middle bridge section (since side recovery is so risky). This bridge can also be dropped through if you're crazy enough.
At this point you're probably thinking to yourself, what's to prevent players from getting a stock ahead and stalling under the stage till time runs out? It's quite simple really. Fireballs resembling Mario's neutral B move in all respects will jump up a short way from the lava on random and fairly frequent occasions. Expect one on screen at all times. They will not hit players unless they are very close to the lava or, on rare occasions, standing on the bridge. If, however, a player is racking up damage stalling under the stage, the fireballs will hit them and, at the expected high percents caused by such a tactic, do an awful lot of knockback, mostly sideways.
Any thoughts?