Any good use of L25 tyranitars/mewtwos (mediocre or poor iv)?

I would tm them and keep them as they can be quite useful but dont power them up. I have ones like that and i keep them as they can be quite hard to get but useful

If you already have six high-IV, high-level Tyranitars, then already-traded, low-IV level 25 ones have only one use: the single Larvitar candy you get from sending them to Professor Willow.

If low on potions you can use them as throwaway attackers before transferring. That's about it. Absolutely not worth any type of resource if you have a team of good Ttars/M2s besides the traded ones.

They can be used to fill out your "B" team for short-man raids when re-entering will be necessary. Sometimes (e.g. against HP-buffed Mewtwo), it's even useful to have a "C" team. But if you already have an army of those guys, and are unlikely to ever use these particular ones, you might as well reduce your clutter and collect the single candy per mon for transferring them.