[email protected] Orb
252 Atk/252 Spd/4 Def
Brave Bird - Has great damage, and with that kind of defense, he's not going to survive long, so the recoil doesn't matter too much.
U-Turn - Swellow is insanely fast, so U-Turn is always a good choice as it allows for some free damage and quick switch into a tank like Chansey or a rocky helmet Skarmory.
Protect/Substitute - As I mentioned earlier, Swellow doesn't have much bulk, but for the burn orb to take effect, you need to wait a turn, and protect allows you to do so without getting OHKOd. ( I prefer protect over substitute because you only need to stall for one turn, and substitute makes you take damage, and with the burn, the brave bird, and the substitute, you might kill yourself. The priority on protect doesn't matter too much, because like I said earlier, you're not going to get outspend by much.)
Return - Return is Swellow's most powerful physical normal move, and because this set is physical, a move like boomburst wouldn't be practical.