Funny thing is since Donphan is coming back for the league, why are people acting like it was part of his Johto team? Donphan may be "a" Johto Pokemon, but that doesn't mean it is part of his old Johto team.

For example, if you go back to watch the Johto saga, Ash has NO Donphan on his team. He has a Phanpy, but absolutely NO Donphan. So how is Donphan part of Ash's Johto team? That doesn't even make sense.

So when Ash uses Donphan in DP, I will consider it a tribute to his AG team, along with Corphish, Torkoal and Glalie, (and hopefully Sceptile/Swellow)

The only reason Donphan is strong is its because all of Ash's AG Pokemon were strong, and it was not part of his Johto team.