Both Dry Bowser and
the summoned Koopaling pair must be defeated in order to end the battle.
When
he summons the Koopalings, they behave like they do in their previous battles with two exceptions (Wendy will not attack Roy if she is hit by one of his attacks; Ludwig and Larry don't use battle cards).
Not exact matches
Occasionally, he'll
summon a pair of
Koopalings (Wendy and Roy, or Larry and Ludwig) from portals to assist him, all of which are at level 46.