user3872: I'm trying to form a 1d4 repertoire (exculsively 1e4 player) around the Catalan Opening. What are some lines that Catalan players play against the KID and slav defense(it seems the normal catalan setup isn't very effective against the slav?). I know this is an open question but I do want lines in the spirit of the Catalan if possible. Thanks.

user11726: This is the exact situation where I found myself and I decided to employ 
the following move order/repertoire to keep me in the spirit of the Catalan.

King's Indian defence

Against the King's Indian Defence you can use the fianchetto variation (which requires studying the Panno variations from the black side), which is actually quite solid and positional.
[fen ""]

1.d4 Nf6 2.c4 g6 3.Nf3 Bg7 4.g3 d6 5.Bg2 0-0 6.0-0 Nc6 

The above can be met in many different ways: there are 7.h3 lines, 7.Nc3, 7.Qc2 and so forth (you should dig into a little theory here). Notice that 3.Nf3 avoids forcing Grünfeld lines that could occur after 3.Nc3 (3...d5 4.cxd5 Nxd5 5.e4 Nxc3 bxc3 6.c5) because there is in fact no Knight on c3 to be exchanged after 5.e4.
The fianchetto variation moreover avoids the automatic plan by Black in the standard variations of the King's Indian (Mar de la Plata) with f5-f4-g5-g4, as the construction
with g3-Bg2 by White makes it really hard to sac-sac-checkmate the King.

Slav

To be honest the best way to meet the Slav is to play the main line, as it gives
White always a slight edge and if well played Black must defend (though it is by 
all means very robust and solid for the second player). Here it is important to 
go 3.Nf3 instead of 3.Nc3 to avoid the Winawer gambit 3...e5 (well, unless you want to play against it and feel comfortable).
[fen ""]

1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 dxc4 5.a4 Bf5 6.e3 e6 7. Bxc4 

and the standard plan is to play Qe2 and then e4-e5 (at the right moment) followed by Bd3 and attack on the Black King. There are fianchetto lines against the Slav as well, however, if you really feel the need to play fianchetto all the times.

3872: <p>I'm trying to form a 1d4 repertoire (exculsively 1e4 player) around the Catalan Opening. What are some lines that Catalan players play against the KID and slav defense(it seems the normal catalan setup isn't very effective against the slav?). I know this is an open question but I do want lines in the spirit of the Catalan if possible. Thanks.</p>
 11726: <p>This is the exact situation where I found myself and I decided to employ 
the following move order/repertoire to keep me in the spirit of the Catalan.</p>

<ul>
<li><h2>King's Indian defence</h2></li>
</ul>

<p>Against the King's Indian Defence you can use the fianchetto variation (which requires studying the Panno variations from the black side), which is actually quite solid and positional.</p>

<pre><code>[fen ""]

1.d4 Nf6 2.c4 g6 3.Nf3 Bg7 4.g3 d6 5.Bg2 0-0 6.0-0 Nc6 
</code></pre>

<p>The above can be met in many different ways: there are 7.h3 lines, 7.Nc3, 7.Qc2 and so forth (you should dig into a little theory here). Notice that 3.Nf3 avoids forcing Grünfeld lines that could occur after 3.Nc3 (3...d5 4.cxd5 Nxd5 5.e4 Nxc3 bxc3 6.c5) because there is in fact no Knight on c3 to be exchanged after 5.e4.
The fianchetto variation moreover avoids the automatic plan by Black in the standard variations of the King's Indian (Mar de la Plata) with f5-f4-g5-g4, as the construction
with g3-Bg2 by White makes it really hard to sac-sac-checkmate the King.</p>

<ul>
<li><h2>Slav</h2></li>
</ul>

<p>To be honest the best way to meet the Slav is to play the main line, as it gives
White always a slight edge and if well played Black must defend (though it is by 
all means very robust and solid for the second player). Here it is important to 
go 3.Nf3 instead of 3.Nc3 to avoid the Winawer gambit 3...e5 (well, unless you want to play against it and feel comfortable).</p>

<pre><code>[fen ""]

1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 dxc4 5.a4 Bf5 6.e3 e6 7. Bxc4 
</code></pre>

<p>and the standard plan is to play Qe2 and then e4-e5 (at the right moment) followed by Bd3 and attack on the Black King. There are fianchetto lines against the Slav as well, however, if you really feel the need to play fianchetto all the times.</p>
