I saw the weirdest Kecleon set today on rating battle...
Kecleon @ Sitrus Berry
Protean
Toxic
Shadow Sneak
Recover
???
I led with my Mega Kangaskhan, they led with this Kecleon. Mega Evolved and used double Fake Out the first turn. I thought double Power-up Punch would be enough to take it out, and it would have been, if not for the random Sitrus Berry. Then they Toxic'd me. On the next turn, I don't know why I didn't just go for the Sucker Punch (I guess I was expecting the Protect) so I went for Return. But this Kecleon used Shadow Sneak, which of course didn't affect me, but because of Protean, my Return didn't affect IT either. So on the next turn, I really don't know what I was thinking this time, because I used Return again. I think my line of reasoning was that Kecleon was going to Protean-change to another type and I could hit it with Return again, but since I am faster that wouldn't have even worked, so I don't know what I was thinking. I think I was just shocked that I was getting owned by a Kecleon, so I wasn't thinking -_-
Anyway, Return didn't work (as is to be expected) but then Kecleon used Recover. At this point, Toxic damage is racking up. So now, I really did start thinking again, and I thought "Okay, my opponent probably doesn't expect me to have Sucker Punch, otherwise I would have used it by now. So the natural choice would be to Shadow Sneak to avoid the Return again." Which is exactly what happened. I KO'ed the Kecleon and breathed a sigh of relief.
Anyway, that's my little anecdote. But yeah, that set... I don't know if was meant to take on Mega Kangaskhan or not, but it was effective in this battle.