Pinsir

He'll be OK against Mewtwo, but he only does neutral damage to Lugia because of flying. T-Tars are by far the best bets.

Imo:
Can be used in larger raid group (18-20); DPS over the first 3-4 pokemons is important as you seldom use more than half your team.

Smaller groups (15 or lower) you probably want some more bulk in order not to faint with all six.

Lugia: no real use. however Celebi and mew maybe.

How is raiding in your area? if loads of people I would have 2-3 glass cannons.

I believe out of all these, Houndoom with Snarl/FP will deal the most DPS overall, followed by Pinsir and Scizor with X-Scissor (only against Mewtwo), and then the B/C Tyranitars.
Being able to survive is of course important, which is where Tyranitars' bulk comes in handy in slots 5 and 6.

Pinsir would be a better option for Focus Blast Mewtwo as he will resist it. Otherwise, Tyranitar and Scizors are at the top for countering Mewtwo, I guess

I doubt the total damage it can make before faint as compared with other good counters as it will occupy a position out of 6. I don't want to risk to rejoin the battle.