So looking at making a full set of monocolors already got the green built and ideas for red and black but what do I do with blue and white and how to improve black and red
You should go for a lifegain/pillow fort deck for white
Gain enough life to be able or survive enough turns to cast big creatures (colorless or white) ie. {Serra avatar}, {any of the collosseses}...
And ajanis ... Lots And lots of ajanis
Just an FYI, stuff like this should go in the "Casual" section or the "Discussion" thread, this area is more for ideas and feedback for the app.
To help though, for the red, you could use {Young Pyromancer}, {Guttersnipe}, and {Monastery Swiftspear}, and for the blue deck, I recommend playing {Talrand, Sky Summoner}.
Red burn, {Lightning Bolt} and friends. {Monastery Swiftspear}, {Goblin Guide}, {Young Pyromancer}. Maybe a {Chandra's Phoenix} or two. Chandra herself. {Chandra, Pyromaster} or {Chandra, the Firebrand} are my favs. {Pyromancer's Gauntlets} perhaps? Also {Anger of the Gods} and {Scouring Sands}. Perhaps {Pyroclasm}.
Blue devotion, {Master of Waves}, {Thassa, God of the Sea}. Counter magic, {Dissolve}, {Counterspell}, maybe {Thassa's Rebuff}. {Fog Bank} and {Guard Gomoza} are fantastic blockers. Maybe {Wall of Frost} as well. Bounce spells to for catching things that make it past your counter magic.
Black devotion, {Gray Merchant of Asphodel}, {Necropotence}, {Erebos, God of the Dead}. Look up some nasty demons. Profit.
I know you have a green one but {Karametra's Acolyte}.
White lifegain, {Anjani's Pridemate}, {Archangel of Thune}, {Soul Mender}, {Nyx-Fleece Ram}. Maybe even {Resolute Archangel}. Some control things like {Banishing Light} and {Oblivion Ring}.
Black devotion
T1 {Gravecrawler}
T2 {Bloodghast}
T3 {Geralf's Messenger}
T4 {Phyrexian Obliterator}
T5 {Gary Merchant of Asphodel}
I have this deck and its alot of fun :)