I'm not super familiar with competitive Pokemon, so I can't give any suggestions for that, but I will say that most of my more "niche" interests either have a 3-5 subscriber community with no activity or no community at all.
But that's a great opportunity to fire up a community yourself to get things kicked off.
I guess splitting a niche into even smaller pieces would be a bad idea for now, so I would suggest having one combined competitive channel to begin with.
Any name suggestions? Should we go with a similar approach as stunfisk and just name it Girafarig/heatmor/whatever or give it a more expressive name like CompetitivePokemon?