>>28394422Smogon has tiers below OU. The whole point of having different tiers and rulesets made for each tier are done so you can use your favorites. Illumise is horrible in OU, yes. It's also horrible in VGC. But, Illumise is a pretty decent Baton Passer in PU to my understanding.
There's nothing stopping you from using a lower-tier Pokémon in an upper-tier, either, if you think it suits your team better. Quagsire is considered RU but it gets a decent amount of use in OU due to it covering a niche.
Having tiers gives you extra options. If your favorite is completely unuseable in VGC, you're shit out of luck unless you want to play with a disadvantage. If your favorite is completely unuseable in OU, however, you might be able to use it well in UU, or RU, etc. The only people who really get screwed over are the people whose favorites are banned from OU but aren't good enough to compete in Ubers.
Now, the community will probably look at you harshly for not using OU: The OU, but they're just people, they don't have any actual authority and they can't stop you from playing how you want, so I recommend just ignoring them.
