If you have the full version you can get Tentomon and Viadomon at the end when they invite you to the special island. Tento to the left and viado to the right in special grass patches.
There is a trade for Viadomon for a Smokemon you get from the cave before blueford. It is in the house below blueford before the path to yellowport. If you didnt get a smokemon on the way there is a trade for a Paumon to a smokemon at the end of the cave that links yellowport back to the first baraguru town. You can get a Paumon in the grass patch before going into that cave if you don't want a low level Viadomon since trade lv of your mon=their level.