Details on Lord of Wise
The Kamen Rider-like form that the Four Sages transform into is called Lord of Wise. Though they look like Riders. They are officially Kaijins. The reason why they look like Agastya Base Guards is because of the Production requirements.
Around the time the TV Series Final Arc script was finalized, Superhero Senki staff had the requirement of including Guards for the movie. Fortunately, it was decided that the suits would be shared for two different entities.
The actors who are playing the Four Sages have not been disclosed. But they could be Suit Actors making a cameo.
Each Lord of Wise has a minor difference in the suits with others. Each one uses a different weapon and each one has a name. This one is Lord of Wise Spartan. He has Blue Shoulders. His ability is Power & Defense. He wields a Large Sword and a Battle Ax.
Lord of Wise Highlander - Has a Pink Mantle & Pink Right Shoulder. Uses a Scythe and has some special powers.
Lord of Wise Diago - Has a Golden Mantle & Golden Left Shoulder. He has Super Speed and his weapon is Twin Rapier.
Lord of Wise Kuon - His name means Eternity. Only Kuon's suit doesn't have any modification from the Agastya Base Guard's suit. He uses Twin Swords.