Dragon Bolts (e) are the most effective, however you can use Diamond Bolts (e)
Oh that depends on several things. First off if your a member theirs a wide variety of arrows to use I am a member when i killed him had 70 range at the time and i owned his butt lol it ended to soon. otherwise depending on your range level i would strongly recommend the arrow class that's close to your range level otherwise if your range is high I would recommend using a crossbow and bronze bolts and just kill him that way. I killed him in members world using broad bolts.
lv 48
Mewtwo is at Level 70 when you battle him. You should most likely use you highest level Pokemon that is around level 70.
i recently fought them i think 70-82 somewhere in that range
Your combat level is also dependant on your hitpoints, prayer, range, magic and summoning level. Assuming you had 70 attack, strength and defence, with 10 hitpoints (the lowest level you can have) and the rest of the skills mentioned above at level 1, you would have a combat level of 65. If however you had 70 hitpoints as well, you would be a level 80 combat.
it depends on your range level and what your training on, i cant say exactly what amount
70
A suggestion to get to level 70 is:1-10 Use a sling on goblins in Lumbridge10-20 Level 5 goblins outside of the Grand Exchange and next to Edgeville dungeon which you need brass key for.20-30 Barbarian Village30-40 Hill Giants40-50 Level 30 zombies, level 28 Creepy Crawlers, or level 40 zombies at Stronghold of Security50-70 Level 58 Ice Giants and level 56 Ice Warriors
Range high 50's and 60's close 70's.
Go deep into cerulean cave it'll be level 70 use over level 70 the item to catch is master ball HOPE THIS HELPS
You probally want to use it on mewtwo because it is level 70
You can the highest you can get any skill in Runescape is 99. And the highest combat level you can get is 138.