Is a "serve-switch" considered legal in a tournament? Last week during a match, one of the elders positioned himself to do a backhand serve.... then at the very last minute he "switched" to the forehand and served high. He did like 3 times in the match itself. Even my partner was like "WTF is that serve?".
there is nothing in the rules that governs whether the service is forehand or backhand, nor does it say anything about stance or preparation except that the first forward movement must be continuous and that the feet must be in constant contact to the ground.
given that the server abide to those rules, he can be as creative and unconventional as he can.