Dude, we're talking anime that was generally targeted at little kids but turned out to be rather popular with older kids. There would be no death or, well, making-love-like things in this kind of anime.
Besides, Pokemon do die, but it's highly unlikely there will be enough seasons to kill Pikachu of old age.
I don't think any other method could really be applied in this anime.
BirdLord, really. Pikachu has made rodents much, much cooler. It's cool and cute. Same with any other rodent-y Pokemon.
(Oh why don't they bring out a guinea pig Pokemon??? They're so sweet [I have two of my own, three in the house.])