This song is meant to be played on Capo 3. It's still obviously do-able without but won't sound like the original.
The intro and verses are: F#m/B, G, D, Dsus2. The pre-chorus "nobody said it was easy" part goes: G, D, Dsus2 X2 and then A, A7th. Chorus goes: D, G, D, Dsus2.
If you're playing with a capo this chord should be played on the 5th fret. We're going to call it a F#m/B for simplicity sake :p
Verse: F#m/B, G, D, Dsus2.
Switching from a D to a Dsus2 is very simple. Instead of taking your hands off and repositioning them back on just remove your 2nd finger from the string and keep playing smoothly :)
Pre chorus: G, D, Dsus2 X2 and then A, A7.
Drop your middle finger from the previous A and you've got yourself an A7.
Chorus: D, G, D, Dsus2. Play along with the song to get a feel for everything.
If you have any questions message me or comment. Feel free to request any songs!