In one of my FRLG playthroughs, I used an Exeggutor with Chlorophyll, Sunny Day and Solarbeam. I would first set up Sunny Day, then I would use Solarbeam. With Chlorophyll, I'd outspeed just about anything
If I couldn't use Sunny Day, I would have Psychic and Giga Drain as moves not requiring sun to be up
It was pretty fun to use, if a little clunky. Wanted to use something different, and it worked out greatly

>pic unrelated