You should up the spawning on pixelmon, last night i had to look around for periods of 15min to find just one regular ol' pixelmon. Also, you should up the spawning just a little bit on legendaries, i waited 4 hours untill i gave up, and yes i was in the correct biome.
I have been playing with the configs, Specifically those dealing with spawning trying to dial it in. I think that currently it is in a better state than it was yesterday, As for legendaries I have been doing a lot of research into why we aren't getting them to spawn. I don't have any clue why its not happening.
I've been testing the legendary spawns in Single player, and it doesn't seem that waiting actually helps, so I wouldn't suggest doing that anymore, but I highly suggest that you actually explore other biomes to attempt to spawn legendarys. Spawn rates for legendaries have already been lowered, but it seems they're not wanting to spawn at all, so it's just a waiting game for one to actually spawn at all. (Meaning, we're going to have to be patient to see if one actually does spawn at all)