What if legendary critters were incorporated into the game the same way Pokemon approaches legendary Pokemon. Imagine you go to the raptors near, and every encounter that spawns has (insert small %) to include a legendary raptor. You have to use Peacekeeper, Peacemonger, (or you give the hunter/Big Game Hunter a "detain" ability) to lockup the legendary critter. Bam, now you keep the legendary critter.
Doing this helps subside P2W, and encourages more time actually playing the game for rare units. Madrona could even create special items to boost encounter rates (the same way Z2 allowed SP boost purchases).