Hey there,
Just want to start by saying that I would
keep Life Orb on Genesect. Life Orb really helps with power, as Giga Drain is kinda weak, and it can also be somewhat offset by Giga Drain's healing. It also helps immensely with Genesects wall breaking power. Now like you mentioned, Tornadus-T in the rain is incredibly deadly as it can come in and spam Hurricanes with little fear. I would recommend making Keldeo a
Choice Scarf spread to help with this. In BW2 offensive teams need all the speed they can get, and a Scarf Keldeo will help with your lack of it. Scarf Keldeo gives you a lot of revenge killing capabilities as well, being one of the fastest scarfers in the metagame. Hope these suggestions are helpful, GL!
set

Keldeo @ Choice Scarf
Trait: Justified
EVs: 4 Def / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Surf
- Secret Sword
- Hidden Power [Ice]
- Hydro Pump