Metagross Partner

#4
Tapu Lele's definitely good. However I'd recommend against running 252Atk/252Spe because Metagross plays better as a bulky attacker imo. If you use CB Meta + Lele you hardly need any Attack investment to OHKO or chunk things with Zen Headbutt, so you can run more bulk instead. Likewise with base 70 (iirc) Speed it's not the fastest mon around, so moving some points to bulk (depending on what you want to outspeed; I run 164 Spe to outspeed Scarf Lele in Tailwind) can definitely be beneficial.
 
#7
CB Metagross can be checked by Garchomp, offensive or Will O Wisp Arcanine, Foul Play Mandibuzz, basically anything with Will O Wisp