While this is a good moveset, it's also the most common and predictable moveset on Kecleon. Everyone will anticipate that Skill Swap, and probably just go all out to KO you in one or two hits. Do not fear! Just like with Shuckle, I have raised many Kecleon Specimens.
Firstly, you want a reliable STAB. The most reliable, of course, is Return. If the Happiness isn't quite there, then Slash is a great alternative.
Next, you'll want Substitute. Using Substitute will take out 1/4 of your HP, but is worth the free dummy hit. Also, use Substitute with prediction. If you feel the opponent is going to take a turn to buff or set up something, then activate the Substitute then.
Next, you'll want Focus Punch. Focus Punch and Substitute on Kecleon are like Peanut Butter and Jelly. Due to Kecleon's horrible Speed, he'll move last, and not have to worry about having its Substitute break the turn it makes it. Because of Focus Punch, you'll need a 2-turn charge. When your Sub is up, charge up your punch. The opponent will likely break your Substitute that turn, but because Focus Punch has priority, you get the charged attack first thing next turn. It's a flawless Focus Punch, and very few Pokemon can pull it off.
Finally, you'll want a filler. Probably something to hit Ghosts, seeing as Ghosts are immune to Return, Slash, and Focus Punch. Faint Attack or Shadow Claw will do. Sucker Punch is a risky alternative, but also gives priority. Pick the one you like best.
Kecleon's possibilities are nearly endless, since everything in its movepool can be used to its advantage. Shadow Claw and Skill Swap works wonders, this strategy is great, or a Special Wall set is even possible. This is my personal favorite, and it's great for survival too.