written by @bkertz in the DFS Hero Discord
General Strategy
While the focus for cash games is to play not to lose, in GPPs you are shooting for the moon. You do not want to "play it safe" here. You want to be different with your lineups for GPPs. You will find yourself not cashing quite often in GPPs. This is OK since you should be playing GPPs to win big. If you play the chalk and high projected ownership guys, it makes it harder to win (you have to be absolutely perfect, which is nearly impossible with the variance in baseball). Even if you do win, you'll likely split the winnings. This DOES NOT mean to go crazy and play a bad offense (think the Nationals) against the best pitcher on the slate. This approach is negative EV (expected value) and will rarely, if ever, work.
Stacking
For large GPPs, you need to stack hitters. On DraftKings, you can go 5/3, 5/2/1, 4/4, 4/3/1, etc. The numbers identify how many hitters from each team. For example, in a 5/3 you will have 5 hitters from one team and 3 hitters from a different team. They do not need to be in the same game. For FanDuel, where stacks are limited to a max of 4, you can go 4/4, 4/3/1, etc. Sometimes you can get different stacking a chalk stack (think the Braves in Colorado). While it's best to target the 1-5 hitters in a lineup for stacks, you could take 3-4 of the top projected owned hitters in a lineup and pair them with 1-2 hitters who are projecting to be lower owned.
Pitching
For pitching, leverage the same stats as you would for cash games. If you select pitchers for your GPPs who are projected to be highly owned, you will need to stray further from projected ownership with the hitter stacks you select. Finding pitchers who have a high K% facing teams with a high K%. FanDuel is especially kind to high strikeout pitchers, even if they yield a bunch of hits and walks.
Hitting
For hitting, look to roster stacks in good hitting ballparks (Coors Field, Great American Ballpark, etc.) and those facing weak pitchers. One way to spot pitchers to take advantage of with stacks is to find pitchers with a high BB%. These pitchers tend to put more runners on base, which can turn solo HRs into 2+ run HRs. Ideally you'd compound points here with your stacks (points for the HRs and extra RBIs, plus points for the runners on base).
Leverage
While avoiding bad weather games is the smart play in cash games, you can gain leverage on the field by using players in bad weather games. Let's say the Braves are playing the Rockies in Colorado, but there's a solid chance for rain. If it looks like the field is avoiding this game in what would normally be a smash spot, you can play a Braves stack. This all depends on your tolerance for losing. This is highly risky, and it likely results in a very low scoring lineup. If the game plays and the Braves do well, there will be lower ownership here. Thus, you are competing against fewer lineups that smash and increase your chances for a big win.
GPPs are the place to play the highly volatile players. This doesn't mean filling your entire lineup with highly volatile hitters and pitchers as this would be negative EV. You can sprinkle in the Giancarlo Stantons and hitters of similar style. Pitchers to look for here are the highly volatile but high strikeout potential. Look at guys like Hunter Greene who is capable of a 8+ strikeout game, but is also just as likely to score negative fantasy points.
Wrap-up
Your approach for GPPs should vary depending on the contest type. If you are playing a small, single entry GPP you do not need to stray as far from chalk as you would in a large GPP which allows 150 entries.