GEAR UP 2 is for upgrading 5 powers.
From the menu go to the shop page and simply buy 5 upgrade for you powers.
Every level for each power counts so you can buy he lower ones.
Keep in mind that for "GEAR UP 3" you will need 80 gold ingots as well so I would advise buying every gold ingot in every level you come across a shop to not have to go back and look for the shops later.
For unlocking this you may need to start up a level and then go back to the shop page for the achievement to unlock.