Growlithe and Arcanine come to mind first, also try Houndour/Houndoom, Poochyenna/Mightyenna and the legendary dogs all have/can learn it. There's a lot more, but those are the ones that come to mind first.
Here's a fun site I usually use for questions like this, I know it'll help you, and anyone else, out.
http://pokemon.marriland.com/
There are pokedex's and all sorts of other usefull things for a lot of games. Also, try
http://www.serebii.net/index2.shtml
For any/all extra info you may need.
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special rend and roar of time special rend and roar of time special rend and roar of time REAL ANSWERnone of those are real the move set is splash,tackle,& flail.
how o you get a moghty roar in pokemon diamon
I'm pretty sure there is an ability, but I forget what it is.
maybe you could use a Pokemon with the ability shadow tag eg. wynaut, wobbufet block or a move-restricting move
To get the TM Roar There is a guy with a Poochyena on Route 114 talk to him and he will give it to you.