What blue thing? if you mean the castle thing you need the 2 riolius in the side rooms
Lucario is at the Almia Castle and guards the Blue Gem.
You get riolu when you go to Almia Castle to search for the blue gem.
yiu can find an electrode in pultown by a blue building
To get through that blue energy wall in Pokemon Ranger Shadows of Almia in the Almia castle, capture Froslass as a boss, have 2 Riolu's in the party and use it's power.
After you defeat lucario and obtain the blue gem, a quest will be avalible to save a piplup from a pokemon.
If you're asking about the blue crystal in Pokemon Ranger Shadows of Almia, then it's at the top of Almia Castle. To get there you surf with a Floatzel through Crysta Cave then go through Hia Valley then surf through the icy lake and then go all the way to the top of the castle and fight Lucario and then you'll have it.
You go into Almia Castle. Murph is where the Blue Prince's Tear is.
Go to the next room. Ice mentioned a strong Pokemon ahead guarding the Blue Gem. It happens to be Lucario. After you capture it, then a warp hole will appear, allowing you to get back to the entrance.
You will capture lucario when u r gettin da blue gem. Sadly, you cant get it 2 put in ur team. U can get riolu though. Eventually in da storyline u will have to get the blue gem in Almia Castle. Lucario will be a boss battle so watch out!
He's in Almia Castle, near where the blue Tears of Princes was. For 'Murph's Disappearing Act.', unless that wasn't what your asking, if your asking 'Where is Murph so I can do his quest' He's in the first room on the second floor of the Ranger Union. Hope this helps.
Use a flying type Pokemon I would know because I gust beat him. because Lucario is a Fighting and Steel type Pokemon, the best thing to use is a fire type poke assist. it's great that there are many vulpixs at the Almia castle, and you can go back to catch the ninetales. use water poke assist also. flying may help, but it is still a steel type Pokemon. good luck getting the 1st tears of princes, and good luck with the blue gem!!!!!!!!!!!!!!!!!!!!!!!!!!
You need to find 2 Riolus and bring them to the light barrier where you fought with Ice's Pokemon. Then press "A" in front of the barrier.