Offense
Up close, Donvalve is easily a threat to any opponent. Be weary though, as Donvalve doesn't have a totally flawless offense. The opponent is already going to be aware of Don Swing, and Don Don Swing, so whenever you can, land at least Don Swing as many times as possible. Force the opponent to the corner with f.5C, and 2C. If the opponent gets smart and starts jumping, meet them in the air with j.A or the stronger j.C. Donvalve can't build meter as quickly as characters like Watson, Face, and Coyori, so you want to poke as much as you can, while forcing to the corner.
Donvalve has other ways of throwing aside from Don Swing and Don Don Swing. A simple A+B throw can easily build momentum. It causes a hard knockdown, so Donvalve can close in with Catapult Hammer Break, and apply pressure afterwards. Catapult Throw is great, because it has armor (up to a few hits), and serves as an instant corner carry. Be cautious not to abuse this move, as many characters have moves that beat out Catapult Throw. Rely on setting up the move, so that the opponent becomes limited in options to counter.
Donvalve has some tricks that can sometimes prove risky, but are very rewarding and open up ways for him to gain momemtum. After a few pokes and some Catapult throws, using 2A > 5D~41236B can catch opponents who think Donvalve is doing a Catapult Throw. The caveat to this is that if the opponent Gachi Matches that hit from Catapult Hammer, they have the upper advantage and can counter freely. Depending on how the opponent jumps, Donvalve can use the Catapult Hammer Break, and continue pressure. 2A > 6B can work wonders despite 6B being -4 on block. Upon landing, Donvalve can instantly do Don Swing, or Don Don Swing. This tech works anywhere on screen, but is stronger in the corner. The only option the opponent has is to jump, in which Donvalve can bait the jump, and counter with c.5C, or Flying Don Cake.
In Heat Mode, Donvalve becomes an almost unstoppable tank. Use this in conjunction with 6C to beat out any defensive tactics the opponent may muster up. Take caution, as a single throw can take Donvalve (or any character) out of Heat Mode.
Defense
Knowing what Donvalve can do defensively is vital to stealing the opponent's momentum and winning the match. If the opponent attempts to take to the air, and Donvalve is without meter for Flying Don Cake, 4C (or c.5C) can easily beat out or trade many aerial attempts. If the spacing is right, Donvalve can anti air with 5A, 2A, and sometimes f.5C and 5D. 5A is amazingly strong against jumping attacks despite its short range.
At crucial moments, Catapult Throw can be very useful as a defensive tool. Knowing when to use it is key. Pay attention to the opponent's rushdown style, and look for pauses and holes in their offense. The same can be said about Don Don Swing, and Flying Don Cake.
Entering Heat Mode serves as a defensive tactic to some extent. Even with Super Armor, Donvalve still takes damage, and is still susceptible to knockdowns.
Neutral
At neutral, Donvalve's main goal is to close the gap between him and his opponent. The majority of his standing normals make him move forward, but the main move that will be used at this range is f.5C. 2C is a helpful attack due to range, but it doesn't move Donvalve forward. At this range, it is very imperative that Catapult Throw is not used, unless the opponent is landing from a jump. Any other time this is used at this range, the opponent has enough time to counter attack.
