I like the gameplay in fusions, it has a very novel battle system that is both very simple, yet has a lot of strategy behind it. Positioning plays a huge deal in the game, as knocking opponents outside of the invisible ring will cause extra damage, and reset their position on the timeline (basically making it so they have longer to wait for their turn). So it's all about trying to get opponents outside the ring, while keeping yourself far from the edge. But position also matters for many other things, like certain moves will only hit opponents close enough to you, or moves will fit in a straight line or arc, so you want to group opponents up in specific ways.
Then there's ki blasts vs physical attacks. Ki blasts cannot be blocked (although super attacks that are a "beam" type can be countered with a beam struggle if the opponent has an appropriate move and enough ki), but they do less knockback. Physical moves do more knockback, but every time you activate one, your opponent gets a chance to block it in a semi-RNG system where you have to predict which direction the attack will hit you. So if you think they'll hit you out the ring, they'd punch you from the left so you'd fly right, thus you want to block left. But they might be planning to hit you towards their teammate instead for a bit of extra damage, so it's semi-RNG in a lot of cases. Of course with AI specifically they don't always follow logic at all, so this block system can feel pure rng in some cases.
My biggest issue with the battle system is the lack of ability to speed up or skip animations. They are very slow, and repetitive battles. In big story battles it's fine to watch everything play out, but the majority of fighting in this game is just grinding or otherwise a filler battle to activate something else. It desperately needed a way to speed these up.
I've gotta give them props for the controls outside of battles too. Flying around a 3D space on a 3DS might seem limiting with only one circle pad (the additional one on new models does nothing) but they really made it work. And they managed to put all the iconic locations into the game by having the world take place in weird space-time distortions so all these landmarks everyone knows are just kind of scattered around.
Customisation is pretty good. Every time you unlock a new (canon) character you get the option to buy their outfit for your own CAC. This even includes things like Saibamen and Cell. So you can have a totally normal looking human on a Saibamen body.
But we're all here for the what-if fusions right? There's some really great ones here. But it's also where my biggest complaints with the game lie...
First of all, fusing and unfusing is such a tedious process. You go through so many confirmation screens, and every single time you do a fusion, or undo one, you have to reassign all the special moves the fusee's had. For a game that has this as a central mechanic, to the point they have a pokédex-esque completion screen for getting every single character, including fusions, the fact they didn't streamline this process is baffling.
Characters can also only fuse with specific characters, which makes sense, it's not like they could design a unique fusion for god knows how many potential results. But I'm not a big fan of the way they did this, because many characters only have 1 potential partner, but that partner can have multiple. Piccolo, for example, can fuse with both Pikkon and Boo saga Gohan (among some others), but both of these characters can ONLY fuse with Piccolo. That means if you want to fuse Piccolo with Pikkon, Gohan is left without a fusion, because you can't make multiple fusions with one character, you have to unfuse them first. There are so many cases like this, where one character can have so many fusion partners, but those partners HAVE to be with this one guy, leaving so many lonely non-fusees.
Then there's a bunch of characters that can't fuse with anyone at all.
Transformations count as their own character slots, and weirdly none of them can fuse with anyone. Even transformations of characters that CAN fuse. Like you can fuse base Kid Gohan and base Kid Trunks, but you can't fuse SSj Kid Gohan and SSj Kid Trunks into the Super Saiyan version of that very fusion. Literally all they'd have had to do is change the hair to blonde!
These are technically lies. Your OC can fuse with literally any character in the game. Of course because you get to design your OC with gender, hair style, and even race, they can't have unique designs. Whenever you fuse your character it's basically just your character + the fusion choice's hair style, with both their hair colour and yours thrown in (think how Gotenks has black and lavender hair). So if you decide to fuse your OC with Tenshinhan, you literally just create a bald version of your character lol. They're also the only ones able to fuse with the transformed characters. Even their name stays exactly the same, and their place in your "pokédex" is always 000. It's clear that OC + anyone is not supposed to be a real "fusion", but more like a power-up for your OC. I think this is a great way to do it since any other system would be like not letting your OC fuse with anyone, having a set design for them so they can make specific fusions with specific characters, or something.
You might look at the character list and go "holy shit there's over 1000 characters in this game!", and...yeah kinda. There's even some very interesting picks, like Bra and Gine. But only the first 110 or so are canon show characters (plus a handful of game-specific main characters). Then there's maybe 50-60 fusions of these canon characters. The rest of this millennial roster are pure made up characters. And I get it, you gotta have filler characters to pad out those filler fights. Some of them even get a bit of story in the game, like a female version of the Ginyu Force. But why the hell are their fusions so complex? These no need at all for these characters nobody even wants to use to have literal entire fusion trees with a ton of criteria for each one. Like let's say you want to fuse Jerry with Todd, but before you do that Jerry must have previously fused with Jeff, and Todd must have previously fused with Sarah. So now that you've done both of those fusions, you have to unfuse them (keep in mind the annoying reassigning of special moves every time) and now you try to fuse Jerry and Todd, but you still can't because first Todd needs to know this specific move! Why the hell did they make such intricate and convoluted fusion trees for these literal who characters?? Why is 80% of the roster just padding with weird models nobody gives a crap about? Literally the only thing it does is make the roster LOOK bigger, and make 100% completion not worth it.
If they just made it so that none of the game-only characters could fuse, except maybe a few unique ones that get spotlight in side quests, and make even just 50 more unique versions of canon characters, it'd have been so much better!
In short? This game is a fusion of a great concept with horrible execution, and fun but slow gameplay with no way to mitigate the pacing.
Then there's ki blasts vs physical attacks. Ki blasts cannot be blocked (although super attacks that are a "beam" type can be countered with a beam struggle if the opponent has an appropriate move and enough ki), but they do less knockback. Physical moves do more knockback, but every time you activate one, your opponent gets a chance to block it in a semi-RNG system where you have to predict which direction the attack will hit you. So if you think they'll hit you out the ring, they'd punch you from the left so you'd fly right, thus you want to block left. But they might be planning to hit you towards their teammate instead for a bit of extra damage, so it's semi-RNG in a lot of cases. Of course with AI specifically they don't always follow logic at all, so this block system can feel pure rng in some cases.
My biggest issue with the battle system is the lack of ability to speed up or skip animations. They are very slow, and repetitive battles. In big story battles it's fine to watch everything play out, but the majority of fighting in this game is just grinding or otherwise a filler battle to activate something else. It desperately needed a way to speed these up.
I've gotta give them props for the controls outside of battles too. Flying around a 3D space on a 3DS might seem limiting with only one circle pad (the additional one on new models does nothing) but they really made it work. And they managed to put all the iconic locations into the game by having the world take place in weird space-time distortions so all these landmarks everyone knows are just kind of scattered around.
Customisation is pretty good. Every time you unlock a new (canon) character you get the option to buy their outfit for your own CAC. This even includes things like Saibamen and Cell. So you can have a totally normal looking human on a Saibamen body.
But we're all here for the what-if fusions right? There's some really great ones here. But it's also where my biggest complaints with the game lie...
First of all, fusing and unfusing is such a tedious process. You go through so many confirmation screens, and every single time you do a fusion, or undo one, you have to reassign all the special moves the fusee's had. For a game that has this as a central mechanic, to the point they have a pokédex-esque completion screen for getting every single character, including fusions, the fact they didn't streamline this process is baffling.
Characters can also only fuse with specific characters, which makes sense, it's not like they could design a unique fusion for god knows how many potential results. But I'm not a big fan of the way they did this, because many characters only have 1 potential partner, but that partner can have multiple. Piccolo, for example, can fuse with both Pikkon and Boo saga Gohan (among some others), but both of these characters can ONLY fuse with Piccolo. That means if you want to fuse Piccolo with Pikkon, Gohan is left without a fusion, because you can't make multiple fusions with one character, you have to unfuse them first. There are so many cases like this, where one character can have so many fusion partners, but those partners HAVE to be with this one guy, leaving so many lonely non-fusees.
Then there's a bunch of characters that can't fuse with anyone at all.
Transformations count as their own character slots, and weirdly none of them can fuse with anyone. Even transformations of characters that CAN fuse. Like you can fuse base Kid Gohan and base Kid Trunks, but you can't fuse SSj Kid Gohan and SSj Kid Trunks into the Super Saiyan version of that very fusion. Literally all they'd have had to do is change the hair to blonde!
These are technically lies. Your OC can fuse with literally any character in the game. Of course because you get to design your OC with gender, hair style, and even race, they can't have unique designs. Whenever you fuse your character it's basically just your character + the fusion choice's hair style, with both their hair colour and yours thrown in (think how Gotenks has black and lavender hair). So if you decide to fuse your OC with Tenshinhan, you literally just create a bald version of your character lol. They're also the only ones able to fuse with the transformed characters. Even their name stays exactly the same, and their place in your "pokédex" is always 000. It's clear that OC + anyone is not supposed to be a real "fusion", but more like a power-up for your OC. I think this is a great way to do it since any other system would be like not letting your OC fuse with anyone, having a set design for them so they can make specific fusions with specific characters, or something.
You might look at the character list and go "holy shit there's over 1000 characters in this game!", and...yeah kinda. There's even some very interesting picks, like Bra and Gine. But only the first 110 or so are canon show characters (plus a handful of game-specific main characters). Then there's maybe 50-60 fusions of these canon characters. The rest of this millennial roster are pure made up characters. And I get it, you gotta have filler characters to pad out those filler fights. Some of them even get a bit of story in the game, like a female version of the Ginyu Force. But why the hell are their fusions so complex? These no need at all for these characters nobody even wants to use to have literal entire fusion trees with a ton of criteria for each one. Like let's say you want to fuse Jerry with Todd, but before you do that Jerry must have previously fused with Jeff, and Todd must have previously fused with Sarah. So now that you've done both of those fusions, you have to unfuse them (keep in mind the annoying reassigning of special moves every time) and now you try to fuse Jerry and Todd, but you still can't because first Todd needs to know this specific move! Why the hell did they make such intricate and convoluted fusion trees for these literal who characters?? Why is 80% of the roster just padding with weird models nobody gives a crap about? Literally the only thing it does is make the roster LOOK bigger, and make 100% completion not worth it.
If they just made it so that none of the game-only characters could fuse, except maybe a few unique ones that get spotlight in side quests, and make even just 50 more unique versions of canon characters, it'd have been so much better!
In short? This game is a fusion of a great concept with horrible execution, and fun but slow gameplay with no way to mitigate the pacing.