DBFZ/Master Roshi/Strategy

General Tactics

Team positioning

Point

Roshi's assist makes him much more valuable further back on your team. Do yourself a favor and don't put him here.

Mid

Roshi's best position. Having an assist for neutral lets him do his best work up close, and it also lets the point character use his amazing assist.

Anchor

Roshi has a command grab and great frame traps, which lets him hit opponents when he's by himself. Being anchor gives him a lot of meter to work with, and it also lends his assist to two characters as opposed to one. Mid is generally a stronger position for Roshi.

Picking Teammates

Roshi likes having neutral assists because of how committal his projectiles are. Anything that lets him safely advance is good for him. Ideal blockstun is around 30 frames, as true lockdown assists will render his crossups unusable due to crossup protection. Roshi B helps almost every character in the game, and he isn't picky in terms of teammates himself.

Blockstrings

2L > 5LL > 2M > 5M > 2H > 236L

Roshi's longest gapless blockstring. Works well with assists.

5LLL > 4SD > Assist

Roshi's mixup string. 5LLL pulls opponents out of the corner, allowing for crossups in the corner depending on your assist call timing.

j.M/H > j.236L > Assist

The Leffen, jump-in mixup with an assist. Delay airdash to stay same side, airdash immediately for a crossup.

Frame Traps

Roshi has a plentiful supply of 17f startup moves. Out of M and H normals, these will leave a 2 frame gap on block, which will catch buttons, vanish, and 4-frame reversals.

5LL/5M/2M/6S > 5H/5S: 2-frame gap.
5L/2L > 2M: 1-frame gap.
5H > 5S: 2-frame gap.
5S > 5H/236M: gapless.
5LL/5M/2M/5H/2H > 236M: 2-frame gap.
6S > 6SS: big gap.

This isn't all of his possible frame traps, but it should be enough to get you started. Anything that has 16 or 17 frame startup will frametrap from his normals that have 15 frames of blockstun.

Disengaging

Roshi's 2S allows him to go back to neutral if his pressure fails to secure a hit. He's generally safe when canceling from M/H normals, and he can also gatling into any H/S normals he hasn't yet used in a string. This is most commonly going to end up being his 2H at the end of his gatling table.

Okizeme

Roshi doesn't have a float, which completely eliminates superjump float and superjump IAD mixups. j.2M leaves him at around +41, which is only enough for a safejump. If you have conditioned your opponent enough, you can sneak in an airdash j.4M for a crossup midscreen. Everything else he has is a gimmick.

Safejump OS

Roshi has been gifted the extraordinary ability to ignore delay wakeup mash. Besides the normal j.H~4S reflect OS he has access to, he can also option-select his 214X to eat any attempt besides reflect to get out of pressure. By doing j.M/H~214M, he can armor through any challenges and get a combo on hit while also only staying -5 on block. If you want to spend the assist regardless, you can use 214L instead to retain your Smash for later in the combo.

Tips and Tricks

2H > delay 214S is an amazing ToD starter.
If you're having trouble with Masterful Leap and Reverse Kamehameha in combos, the H follow up to an H button will give you the right option every time (at least when you have Smash).
Reverse Kamehameha can be used just like a beam, vanishing on block after the beam connects will be a true blockstring.
2S's landing recovery is not only cancelable into other H/S normals, it's also cancelable into special moves. If your opponent is trying to run up to you, cancelling into 214L or 214H will stop them dead in their tracks.
214L and 214M will catch buttons after Roshi blocks a vanish. They can be baited with a backdash, but stopping your opponent from pressing buttons on their turn is a great tool for Roshi.
Cancelling into 5HS during a blockstring leaves a big gap but can potentially leave Roshi +2 on block after a j.H.
Microdash 5L anytime that Roshi is +2 will stop both backdash and mashing. The timing is tight but the reward is more than worth it.
Roshi's Masterful Leap is an excellent anti-zoning option. Any character that commits to multi-Ki Blasts will be forced to wait through the entire recovery of the move if you invul through something with it, potentially netting a jump-in punish.
j.2H > SD works from further than you think. This also goes for j.2H > j.2M

Fighting Master Roshi

"Get in the jar, big fella" - HookGangGod

214S can be avoided by backdashing in the air or crouching on the ground. If you're flying as Zamasu you're just out of luck.
Roshi doesn't have any non-committal fullscreen options. Make him come to you.
Even though his superdash is +5 on block, his j.L will not reach in time if you block the SD crouching. He's still free to 2H.