Opinions using Charizard Y in VGC/Doubles
Double Genies + Cresselia (with both Icy Wind/TWave and Trick Room) work extremely well with M-CharY
Lando-T for Intimidate and to spam STAB Earthquakes against opposing Fire types which might wall M-CharY (Heatran, Snarl Entei/Arcanine)
Thundy to prevent any Heatran from using Substitute and to spam TWave (making CharY faster than the opposing pokemon, which should be your goal every match to make sure you can fire off at least one or two strong attacks - probably OHKOs)
With Cress you have the option of going slow or fast mode depending on the matchup and it's one of your safest leads.
PS: ok i know that i might sound stupid when i say double genies works well with M-CharY - because they always perform well - but in this case more than in other cases there are no other pokemon which can accomplish their role in this team better than they do.
Lando-T for Intimidate and to spam STAB Earthquakes against opposing Fire types which might wall M-CharY (Heatran, Snarl Entei/Arcanine)
Thundy to prevent any Heatran from using Substitute and to spam TWave (making CharY faster than the opposing pokemon, which should be your goal every match to make sure you can fire off at least one or two strong attacks - probably OHKOs)
With Cress you have the option of going slow or fast mode depending on the matchup and it's one of your safest leads.
PS: ok i know that i might sound stupid when i say double genies works well with M-CharY - because they always perform well - but in this case more than in other cases there are no other pokemon which can accomplish their role in this team better than they do.
