All power chords (so all chords) strummed together 8 times every time!!!
Intro
-----------------------------\---\
-----------------------------\---\
-----------------------------\---\
---7-x8----------------------\x4-\
---5---7-x8---9-x8---8-x8----\---\
-------5------7------6-------\---\
Verse
-------------------------\------------------------------------
-------------------------\------------------------------------
-------------------------\------------------------------------
-7-x8--------------------\-7-x8-------------------------------
-5----7-x8---9-x8---8-x8-\-5----7-x8---9-x8---10-x8-----------
------5------7------6----\------5------7------8---------------
[ Tab from: https://www.guitartabs.cc/tabs/a/avril_lavigne/sk8er_boi_tab_ver_8.html ]
chorus A
-------------------------\---\--------------------------------
-------------------------\---\--------------------------------
-------------------------\---\--------------------------------
--------5-x8-------------\-x2\--------------------------------
-3-x8---3----8-x8---7-x8-\---\-8-x8---8-x8--------------------
-1-----------6------5----\---\-6------6-----------------------
Chorus B
-------------------------\------------------------------------
-------------------------\------------------------------------
-------------------------\------------------------------------
--------5-x8-------666---\-7-x8---5-x8---3-x8---2-x8----------
-3-x8---3----8-x8--444---\-5------3------1------0-------------
-1-----------6-----------\------------------------------------