So I finally resolved to candy Mega-Beedrill to face the Survival Mode...and it worked surprisingly well!!! I did two runs, with the first stopping at stage 34 (Ampharos), and the second losing to MMY (I started the stage with 12 moves, and it survived with around 500 HP, I think), so with a bit of luck I should be able to finally beat the Survival Mode.
As for M-Pidgeot competition, I did 3 additional attempts, scoring 61k, 62k and 76k. Atm I'm in tier 1, but it won't last long. However, 2MSU+2RML is more than enough for me, so I won't spend additional coins. Speaking of which, I should be around 90k by the end of the day, so for once I'll be ready for tommorow's update ^^