I hate to break it to you MFauli, but Lelouch wasn't as smart as he thought he was. Don't forget that while he dominated one of his siblings in the first few episodes, the second Cornelia came back, she rolled right over him strategically. He had to beat her politically, preying on her weakness, since he couldn't hold a candle to her militarily.

He got owned in China the same way. Lelouch surrounded himself with the right people. 1st/2nd best pilot in the world, best nightmare developer in the world, excellent spies, etc. That and the Geass was the only reason he succeeded at all.

Leila just had her entire squad (minus 1) annihilated over political bullshit. Now that she has full command, she is remedying that by recruiting talented individuals that she finds. If she can keep them under control, we'll see how good she is. Others seem to have faith in her abilities, not just due to her adopted family name. Her HQ staff seem to regard her highly, as the relief was visible once she took full command.