Thanks for the tricks. I know them but... meh. Sometimes it works and give golds, sometimes i just got salt. But actually, I have reached a point where random rainbow is almost useless. My main golds are rainbow level in their teams (yes, Money Tree, Christmas Chainsaw and Camelia are rainbows in my heart) and I can do all the stuff I need easily and hardest missions needs too much rainbows anyway. I'm only aiming for some special rainbows for my teams or my good old Nutaku's rainbow (Hi Kerria and Christmas Rose). But that's not that bad without rainbows. Even golds are more for waifu purpose than actual team needs.
The only actual rainbow I need for my team is Shiro-chan.