arena trap > roar? i know roar > shadow tag + mean look + any other trapping crap for that matter, very uncertain about arena trap... and it's an amazing idea, since dugtrio would sureli be faster than even raikou with the right EVs at level 40...
(and logicali speaking, u can't roar your way out of an arena trap... "entei used roar! dugtrio fled the battle! dugtrio took the whole arena trap with it!!!" <-- wtf?!?!?)
a few things are for sure...
1. dogs run on first sight
2. dogs roar if they can't run
3. dogs retain status and health change
4. dogs are the hardest things to catch in the whole game of pokemon =]
good luck...