So, based on the legendary golems` background, it is quite obvious that Regigigas is man-made. It seems rather strange that it was made a Normal-Type, though.
But if you look at its design, you see a lot of elements.
- The vegetation on its shoulders and legs suggests Grass-Type.
- Its mask, shoulderpads and gray eye mark suggest Steel-Type.
- Its hands, modeled after plugs, suggest Electric-Type.
- Its black lines suggest Dark-Type.
- Its red eye mark suggests Fire/Rock-Type.
- Its blue eye mark suggests Water/Ice-Type.
So, perhaps Regigigas was a combination of several different natural elements from the Pokèmon world, and the mutual cancellation of these elements made it a Normal-Type. Considering that it has Rock, Ice and Steel eye marks would also demonstrate why it is the leader of the other three golems.
But if you look at its design, you see a lot of elements.
- The vegetation on its shoulders and legs suggests Grass-Type.
- Its mask, shoulderpads and gray eye mark suggest Steel-Type.
- Its hands, modeled after plugs, suggest Electric-Type.
- Its black lines suggest Dark-Type.
- Its red eye mark suggests Fire/Rock-Type.
- Its blue eye mark suggests Water/Ice-Type.
So, perhaps Regigigas was a combination of several different natural elements from the Pokèmon world, and the mutual cancellation of these elements made it a Normal-Type. Considering that it has Rock, Ice and Steel eye marks would also demonstrate why it is the leader of the other three golems.