how I think mega evolution should work in GO
if a specific pkmn wins enough individual gym battles, willow should come up after the gym battle and give your pkmn its appropriate mega stone
(for charizard or mewtwo, you're given the choice between X or Y)
rather than have the mega stones be items, they should be awarded to individual pkmn
on the pkmn's stat screen, an icon of the pkmn's mega stone now displays next to its cp value
in battle, there is now a red bar below your special attack bar
this bar is full at the equivalent of 200 energy, which then a mega evolution symbol button appears at the bottom of the screen, tapping it evokes the mega evolution - afterwards, the red bar disappears for the remainder of the gym attack
alternatively, the GOplus' button could be pressed to evoke the mega evolution instead, as a psuedo-mega ring of sorts - it'll begin vibrating and cycling colors when the mega evolution is ready
your pkmn's CP changes to reflect its megaevo's new stats, and its moveset stays the same
if anyone wants to translate the megaevos' base stats to GO format, i pulled these formulas from the silphroad folks
Stamina = 2*HP
Attack = 2*Round(Atk0.5*Sp. Atk0.5+Spd0.5)
Defense = 2*Round(Def0.5*Sp. Def0.5+Spd0.5)
(Attack + IV) * (Defense + IV)0.5 * (Stamina + IV)0.5 * (0.7903)2 / 10 to find the CP at level 40
mega venusaur
max CP 3466
base stamina 160
base attack 238
base defense 260
mega charizard X
max CP 3646
base stamina 156
base attack 280
base defense 214
mega charizard Y
max CP 3590
base stamina 156
base attack 278
base defense 210
mega blastoise
max CP 3611
base stamina 158
base attack 254
base defense 252
mega beedrill
max CP 1237
base stamina 130
base attack 118
base defense 138
*something's wrong here...max CP of base beedrill is 1440, meaning the mega would basically be a downgrade without tweaking to the formulas
mega pidgeot
max CP 2889
base stamina 166
base attack 230
base defense 182
mega alakazam
max CP 2225
base stamina 110
base attack 212
base defense 182
mega slowbro
max CP 3246
base stamina 190
base attack 208
base defense 250
mega gengar
max CP 2637
base stamina 120
base attack 234
base defense 198
mega kangaskhan
max CP 3002
base stamina 210
base attack 194
base defense 220
mega pinsir
max CP 2779
base stamina 130
base attack 222
base defense 228
mega gyarados
max CP 3548
base stamina 190
base attack 226
base defense 256
mega aerodactyl
max CP 2849
base stamina 160
base attack 218
base defense 204
mega mewtwo X
max CP 5490
base stamina 212
base attack 364
base defense 222
mega mewtwo Y
max CP 5302
base stamina 212
base attack 364
base defense 206