i need help with my team

[silverswitch1234]

first of all I dont know the difference between ivs and evs when I say I bosted its stats in this and that I mean I did it in super training and im trying to use this against one of my friends
my team is

metagross lv 52 ( gunna raise the leval)
item leftovers/metagrossite tell me wich ones better
ability clear body
earthquake
bullet punch
hammer arm
iron defense
I boosted the stats in sp defense defense and attak
rayquaza lv 80
item draco plate
ability airlock
outrage
dragon pulce
dragon dance
dragon ascent

blaziken lv 100
item blazikenite (should this be my mega or should metagross be my mega. rayquaza is to prodictable)
ability blaze
brave bird
blaze kick
ember ( I need advice on this one what should i switch it with)
flame charge

me and mt friend play 4 pokemon should my 4th be umbreon, talonflame, arceus, draginite or greninga
if you tell me one tell me a moveset to use
rate my team tell me anything I should change