Oop, there are more cards that didn't make it on the Cardfight wiki.
Source
Besides Blau Dunkelheit, the Blau PG, there is
Grosse Bear
Auto [R]: When this unit attacks, if you have a vanguard with "Blau" in it's card name, this unit gets power +3000 until end of battle.
Polar Stern
Auto [R]: When this unit attacks, if you have a vanguard with "Blau" in it's card name, this unit gets power +3000 until end of battle.
Blade Arm Leprechaun
Auto [R]: [Soul Blast (1)] When this unit boosts a unit with "Blau" in it's card name, you may pay the cost. If you do, the boosted unit gets power +6000 until end of battle.
Flower Ray Leprechaun
Auto [R]: [Counter Blast (1)] When your vanguard with "Blau" in it's card name's attack hits a vanguard, you may pay the cost. If you do, stand this unit and this unit gets power +5000 until end of turn.
Morgenrot
Auto: Pioneer (When a unit of the same clan rides this unit, you may call this unit to a rear-guard circle)
Auto [R]: [Counter Blast (1)] When your vanguard with "Blau" in it's card name's attack hits a vanguard, you may pay the cost. If you do, look at up to three cards from the top of your deck, search for up to one card with "Blau" in it's card name from among them, show it to your opponent, put it into your hand, and shuffle your deck.
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Edit:
I apologize for my explanation of Mont Blaukluger. I made a terrible mistake and read Mont as an on-hit card, not a when-attacking card.
Basically, Mont is similar to that to
Beast Deity, Ethics Buster, the first NG Break Ride. The difference is that while they are both when-attacking effects, Mont uses 1 CB to stand ALL your rearguards while Ethics Buster freely stands your front RGs. This is because Season 3 Beast Deities rely on the effect of others being stood to stand themselves.
What you would want to do is attack with your RGs first and take out the opponent RGs. Then use Mont Blau's effect; all your RGs stand. And if the Mont BreakRide hits with Galaxy over, CB2 and -2 from hand to restand Galaxy once more.